From c563493b639c5182e27cbe1ff85754411036570d Mon Sep 17 00:00:00 2001
From: Miro Richard Eklund <miro.eklund@semantum.fi>
Date: Fri, 27 Jul 2018 14:45:33 +0300
Subject: [PATCH] Add new sysdyn functions details in issue 16 linked below

Multiple functions said to be available in simantics sysdyn
documentation were missing. I added those that I could add, leaving
functions that "cannot be called from functions" unimplemented, such as
"der, initial, terminal, sample, edge, change, reinit, cardinality,
inStream, actualStream"

gitlab #16

Change-Id: Ibd2932683f046e2ab11830fb6dd9f4f6b58c29cb
---
 .../semantum/sysdyn/solver/Environment.java   | 2482 +++++++++--------
 1 file changed, 1339 insertions(+), 1143 deletions(-)

diff --git a/bundles/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java b/bundles/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java
index baf91ac6..74e2ffb7 100644
--- a/bundles/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java
+++ b/bundles/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java
@@ -1,1143 +1,1339 @@
-/*******************************************************************************
- * Copyright (c) 2013 Semantum Oy.
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v1.0
- * which accompanies this distribution, and is available at
- * http://www.eclipse.org/legal/epl-v10.html
- *
- * Contributors:
- *     Semantum Oy - initial API and implementation
- *     VTT Technical Research Centre of Finland - #4488
- *******************************************************************************/
-package fi.semantum.sysdyn.solver;
-
-import fi.semantum.sysdyn.solver.Array.Modifier;
-import gnu.trove.list.array.TIntArrayList;
-import gnu.trove.map.hash.TObjectIntHashMap;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.Map;
-import java.util.Random;
-import java.util.Set;
-import java.util.TreeMap;
-
-interface Fn {
-	public Object evaluate(IEnvironment environment, int argc);
-	public Object evaluateInput(IEnvironment environment, int argPosition);
-	public void setLocals(IEnvironment environment);
-	public int offset();
-	public Variable[] parameters(int args);
-}
-
-abstract class Fn1 implements Fn {
-
-	Variable[] parameters;
-	
-	public Fn1(int pCount) {
-		if(pCount > 0) {
-			parameters = new Variable[pCount];
-			for(int i=0;i<pCount;i++)
-				parameters[i] = new Variable(new VariableBase("", i));
-		}
-	}
-	
-	public int offset() {
-		return 0;
-	}
-	
-	public Variable[] parameters(int argc) {
-		if(parameters != null) return parameters;
-		else {
-			Variable[] ret = new Variable[argc];
-			for(int i=0;i<argc;i++)
-				ret[i] = new Variable(new VariableBase("", i));
-			return ret;
-		}
-	}
-	
-	@Override
-	public void setLocals(IEnvironment environment) {
-	}
-	
-	@Override
-	public Object evaluateInput(IEnvironment environment, int argPosition) {
-		// Function frame size is constant - this is called when padding is needed
-		return null;
-	}
-	
-}
-
-abstract class FnRandom extends Fn1 {
-	
-	protected Random random = null;
-
-	public FnRandom(int pCount) {
-		super(pCount);
-	}
-	
-}
-
-final public class Environment implements IEnvironment, ISystem {
-	
-	final Map<String,Object> named = new HashMap<String,Object>();
-
-	public Model model;
-	public double step;
-	public double time;
-	public boolean initial = true;
-	public int size;
-	
-	public Object[] valueTable;
-	
-	public TObjectIntHashMap<String> keyIndexMap = new TObjectIntHashMap<String>(); 
-
-	HashMap<String,TreeMap<Double,Double>> history = new HashMap<String,TreeMap<Double,Double>>();
-
-	public Environment(Model model, double step, double start) {
-		this.model = model;
-		this.step = step;
-		this.time = start;
-		
-		model.functions.put("sin", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.sin(x);
-			}
-			
-		});
-		model.functions.put("cos", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.cos(x);
-			}
-			
-		});
-		model.functions.put("tan", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.tan(x);
-			}
-			
-		});
-		model.functions.put("asin", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.asin(x);
-			}
-			
-		});
-		model.functions.put("acos", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.acos(x);
-			}
-			
-		});
-		model.functions.put("atan", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.atan(x);
-			}
-			
-		});
-		model.functions.put("toRadians", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.toRadians(x);
-			}
-			
-		});
-		model.functions.put("toDegrees", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.toDegrees(x);
-			}
-			
-		});
-		model.functions.put("exp", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.exp(x);
-			}
-			
-		});
-		model.functions.put("log", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.log(x);
-			}
-			
-		});
-		model.functions.put("log10", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.log10(x);
-			}
-			
-		});
-		model.functions.put("sqrt", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.sqrt(x);
-			}
-			
-		});
-		model.functions.put("cbrt", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.cbrt(x);
-			}
-			
-		});
-		model.functions.put("mod", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Double y = (Double)environment.getValue(1);
-				return mod(x, y);
-			}
-
-			double mod(double x, double y) {
-				return x - Math.floor(x/y)*y;
-			}
-
-		});
-		model.functions.put("rem", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Double y = (Double)environment.getValue(1);
-				return Math.IEEEremainder(x, y);
-			}
-
-		});
-		model.functions.put("ceil", new Fn1(1) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object value = environment.getValue(0);
-				if(value instanceof Double) {
-					return Math.ceil((Double)value);
-				} else if(value instanceof Array) {
-					return ((Array)value).copy(new Modifier() {
-
-						@Override
-						public Object modify(Object o) {
-							if(o instanceof Double) {
-								return Math.ceil((Double)o);
-							} else {
-								throw new IllegalStateException();
-							}
-						}
-						
-					});
-				} else {
-					throw new IllegalStateException();
-				}
-			}
-			
-		});
-		model.functions.put("floor", new Fn1(1) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object value = environment.getValue(0);
-				if(value instanceof Double) {
-					return Math.floor((Double)value);
-				} else if(value instanceof Array) {
-					return ((Array)value).copy(new Modifier() {
-
-						@Override
-						public Object modify(Object o) {
-							if(o instanceof Double) {
-								return Math.floor((Double)o);
-							} else {
-								throw new IllegalStateException();
-							}
-						}
-						
-					});
-				} else {
-					throw new IllegalStateException();
-				}
-			}
-			
-		});
-		model.functions.put("rint", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.rint(x);
-			}
-			
-		});
-		model.functions.put("atan2", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Double y = (Double)environment.getValue(1);
-				return Math.atan2(x, y);
-			}
-			
-		});
-		model.functions.put("pow", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Double y = (Double)environment.getValue(1);
-				return Math.pow(x, y);
-			}
-			
-		});
-		model.functions.put("round", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				long result = Math.round(x); 
-				return (int)result;
-			}
-			
-		});
-
-		model.functions.put("abs", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object o = environment.getValue(0);
-				if(o instanceof Double) {
-					return Math.abs((Double)o);
-				} else if (o instanceof Integer) {
-					return Math.abs((Integer)o);
-				} else {
-					throw new IllegalStateException("Unsupported argument to abs: " + o);
-				}
-			}
-			
-		});
-
-		model.functions.put("min", new Fn1(5) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object first = environment.getValue(0);
-				if(first instanceof Double) {
-					Double result = (Double)first;
-					for(int i=1;i<argc;i++) {
-						Double d = (Double)environment.getValue(i);
-						if(d < result) result = d;
-					}
-					return result;
-				} else if (first instanceof Integer) {
-					Integer result = (Integer )first;
-					for(int i=1;i<argc;i++) {
-						Integer  d = (Integer )environment.getValue(i);
-						if(d < result) result = d;
-					}
-					return result;
-				} else {
-					throw new IllegalStateException("Unsupported argument to min: " + first);
-				}
-			}
-			
-		});
-		model.functions.put("max", new Fn1(5) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object first = environment.getValue(0);
-				if(first instanceof Double) {
-					Double result = (Double)first;
-					for(int i=1;i<argc;i++) {
-						Double d = (Double)environment.getValue(i);
-						if(d > result) result = d;
-					}
-					return result;
-				} else if (first instanceof Integer) {
-					Integer result = (Integer )first;
-					for(int i=1;i<argc;i++) {
-						Integer  d = (Integer )environment.getValue(i);
-						if(d > result) result = d;
-					}
-					return result;
-				} else {
-					throw new IllegalStateException("Unsupported argument to max: " + first);
-				}
-			}
-			
-		});
-
-		model.functions.put("ulp", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.ulp(x);
-			}
-			
-		});
-
-		model.functions.put("signum", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.signum(x);
-			}
-			
-		});
-
-		model.functions.put("sinh", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.sinh(x);
-			}
-			
-		});
-
-		model.functions.put("cosh", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.cosh(x);
-			}
-			
-		});
-		
-		model.functions.put("tanh", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.tanh(x);
-			}
-			
-		});
-
-		model.functions.put("hypot", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Double y = (Double)environment.getValue(1);
-				return Math.hypot(x, y);
-			}
-			
-		});
-
-		model.functions.put("expm1", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.expm1(x);
-			}
-			
-		});
-
-		model.functions.put("log1p", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.log1p(x);
-			}
-			
-		});
-
-		model.functions.put("copySign", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Double y = (Double)environment.getValue(1);
-				return Math.copySign(x, y);
-			}
-			
-		});
-
-		model.functions.put("getExponent", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.getExponent(x);
-			}
-			
-		});
-
-		model.functions.put("nextAfter", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Double y = (Double)environment.getValue(1);
-				return Math.nextAfter(x, y);
-			}
-			
-		});
-
-		model.functions.put("nextUp", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				return Math.nextUp(x);
-			}
-			
-		});
-
-		model.functions.put("scalb", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double x = (Double)environment.getValue(0);
-				Integer y = (Integer)environment.getValue(1);
-				return Math.scalb(x, y);
-			}
-			
-		});
-
-		model.functions.put("size", new Fn1(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Array array = (Array)environment.getValue(0);
-				Double col = (Double)environment.getValue(1);
-				return Double.valueOf(array.size(col.intValue()));
-			}
-			
-		});
-		model.functions.put("zidz", new Fn1(2) {
-
-			private Object evaluate(Double p1, Double p2) {
-				if(Math.abs(p2) < 1e-12) return 0.0;
-				else return p1 / p2;
-			}
-			
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object o1 = environment.getValue(0);
-				Object o2 = environment.getValue(1);
-				
-				if(o1 instanceof Double && o2 instanceof Double) {
-					return evaluate((Double)o1, (Double)o2);
-				}
-				if(o1 instanceof Array && o2 instanceof Array) {
-					Array la = (Array)o1;
-					Array ra = (Array)o2;
-					Collection<Object> lae = la.elements();
-					Collection<Object> rae = ra.elements();
-					if(lae.size() != rae.size()) throw new UnsupportedOperationException();
-					Iterator<Object> li = lae.iterator();
-					Iterator<Object> ri = rae.iterator();
-					Array result = new Array();
-					for(int i=0;i<lae.size();i++) {
-						double ld = (Double)li.next();
-						double rd = (Double)ri.next();
-						result.addElement(evaluate(ld,rd));
-					}
-					return result;
-				}
-				throw new IllegalStateException();
-				
-				
-			}
-			
-		});
-		model.functions.put("xidz", new Fn1(3) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double p1 = (Double)environment.getValue(0);
-				Double p2 = (Double)environment.getValue(1);
-				Double x = (Double)environment.getValue(2);
-				if(Math.abs(p2) < 1e-12) return x;
-				else return p1 / p2;
-			}
-			
-		});
-		model.functions.put("availabilityExternal", new Fn1(4) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double numberOfDays = (Double)environment.getValue(0);
-				Double numberOfDesigners = (Double)environment.getValue(1);
-				@SuppressWarnings("unused")
-				Double rseed = (Double)environment.getValue(2);
-				@SuppressWarnings("unused")
-				Array availability = (Array)environment.getValue(3);
-				Array result = new Array();
-				for(int i=0;i<numberOfDays.intValue()*numberOfDesigners.intValue();i++) {
-					result.addElement(Math.random());
-				}
-				return result;
-			}
-			
-		});
-		model.functions.put("pre", new Fn1(1) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				
-				return (Double)environment.getValue(0);
-				
-			}
-			
-		});
-		model.functions.put("fill", new Fn1(3) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double value = (Double)environment.getValue(0);
-				Double dim1 = (Double)environment.getValue(1);
-				if(argc == 2) {
-					Array result = new Array();
-					for(int i=0;i<dim1.intValue();i++) {
-						result.addElement(value);
-					}
-					return result;
-				} else if(argc == 3) {
-					Double dim2 = (Double)environment.getValue(2);
-					Array result = new Array();
-					for(int i=0;i<dim1.intValue();i++) {
-						Array array = new Array();
-						for(int j=0;j<dim2.intValue();j++) {
-							array.addElement(value);
-						}
-						result.addElement(array);
-					}
-					return result;
-				} else throw new UnsupportedOperationException();
-			}
-			
-		});
-		model.functions.put("randomNumber", new FnRandom(2) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double seed = (Double)environment.getValue(0);
-				
-				if (random == null) {
-					random = new Random(Double.doubleToLongBits(seed));
-				}
-				
-				return random.nextDouble();
-			}
-			
-		});
-		model.functions.put("randomUniform", new FnRandom(4) {
-			
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double min = (Double)environment.getValue(0);
-				Double max = (Double)environment.getValue(1);
-				Double seed = (Double)environment.getValue(2);
-				
-				// the fourth parameter should be "time" and is only necessary
-				// because sysdyn treats all functions as side-effect-free and
-				// does not evaluate a function "needlessly" if the parameters
-				// do not change. the parameter does not actually do anything
-				// though so we can safely ignore it here
-				
-				if (random == null) {
-					random = new Random(Double.doubleToLongBits(seed));
-				}
-				return random.nextDouble() * (max - min) + min;
-			}
-			
-		});
-		model.functions.put("randomNormal", new FnRandom(6) {
-			
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Double min = (Double)environment.getValue(0);
-				Double max = (Double)environment.getValue(1);
-				Double mean = (Double)environment.getValue(2);
-				Double stdev = (Double)environment.getValue(3);
-				Double seed = (Double)environment.getValue(4);
-				
-				if (random == null) {
-					random = new Random(Double.doubleToLongBits(seed));
-				}
-				
-				// TODO: use an actual library for this stuff
-				
-				return NormalDistribution.uniformVariableToNormal(min, max, mean, stdev, random.nextDouble());
-			}
-			
-		});
-		model.functions.put("initial", new Fn1(0) {
-
-			@Override
-			public Object evaluate(IEnvironment _environment, int argc) {
-				return _environment.getSystem().initial();
-			}
-			
-		});
-		model.functions.put("noEvent", new Fn1(1) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				
-				return environment.getValue(0);
-				
-			}
-			
-		});
-		model.functions.put("integer", new Fn1(1) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object value = environment.getValue(0);
-				if(value instanceof Double) {
-					double d = ((Double)value).intValue(); 
-					return d;
-				} else if(value instanceof Array) {
-					return ((Array)value).copy(new Modifier() {
-
-						@Override
-						public Object modify(Object o) {
-							if(o instanceof Double) {
-								double d = ((Double)o).intValue(); 
-								return d;
-							} else {
-								throw new IllegalStateException();
-							}
-						}
-						
-					});
-				} else {
-					throw new IllegalStateException();
-				}
-			}
-			
-		});
-		model.functions.put("sum", new Fn1(1) {
-
-			public double sum(Array a) {
-				double res = 0;
-				for(Object element : a.elements()) {
-					if(element instanceof Array) {
-						res += sum((Array)element);
-					} else if(element instanceof Double) {
-						res += (Double)element;
-					} else {
-						throw new IllegalStateException("Tried to sum a non-numerical array");
-					}
-				}
-				return res;
-			}
-			
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				Object value = environment.getValue(0);
-				if(value instanceof Double) return (Double)value;
-				Array arr = (Array)value;
-				return sum(arr);
-			}
-			
-		});
-		model.functions.put("ones", new Fn1(-1) {
-
-			private Array make(int[] dims, int pos) {
-				Array result = new Array();
-				int d = dims[pos];
-				if(pos == dims.length - 1) {
-					for(int i=0;i<d;i++) result.addElement(1.0);
-				} else {
-					for(int i=0;i<d;i++) result.addElement(make(dims, pos+1));
-				}
-				return result;
-			}
-			
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				int[] dims = new int[argc];
-				for(int i=0;i<argc;i++) {
-					Double d = (Double)environment.getValue(i);
-					dims[i] = d.intValue();
-				}
-				return make(dims, 0);
-			}
-			
-		});
-		model.functions.put("zeros", new Fn1(-1) {
-
-			private Array make(int[] dims, int pos) {
-				Array result = new Array();
-				int d = dims[pos];
-				if(pos == dims.length - 1) {
-					for(int i=0;i<d;i++) result.addElement(0.0);
-				} else {
-					for(int i=0;i<d;i++) result.addElement(make(dims, pos+1));
-				}
-				return result;
-			}
-			
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				int[] dims = new int[argc];
-				for(int i=0;i<argc;i++) {
-					Double d = (Double)environment.getValue(i);
-					dims[i] = d.intValue();
-				}
-				return make(dims, 0);
-			}
-			
-		});
-		model.functions.put("transpose", new Fn1(1) {
-
-			@Override
-			public Object evaluate(IEnvironment environment, int argc) {
-				
-				Array array = (Array)environment.getValue(0);
-				return array.transposed();
-				
-			}
-			
-		});
-		model.functions.put("delay", new Fn1(4) {
-			
-			@Override
-			public Object evaluate(IEnvironment _environment, int argc) {
-			
-				String ident = (String)_environment.getValue(0);
-				Double value = (Double)_environment.getValue(1);
-				Double p1 = (Double)_environment.getValue(2);
-				
-				ISystem system = _environment.getSystem();
-				
-				TreeMap<Double,Double> history = system.getHistory(ident);
-				double time = system.time();
-				
-				history.put(time, value);
-				
-				Double key = history.ceilingKey(time-p1);
-				
-				return history.get(key);
-				
-			}
-			
-		});		
-		model.functions.put("cat", new Fn1(10) {
-			
-			@Override
-			public Object evaluate(IEnvironment _environment, int argc) {
-			
-				Double dim = (Double)_environment.getValue(0);
-				
-				Array array = new Array();
-				for(int i=1;i<argc;i++) {
-					Object ar = _environment.getValue(i);
-					if (ar instanceof Array) {
-						Array a = (Array)ar;
-						for(Object o : a.elements())
-							array.addElement(o);
-					} else {
-						throw new IllegalStateException();
-					}
-				}
-				
-				return array;
-				
-			}
-			
-		});		
-	}
-	
-	public TreeMap<Double,Double> getHistory(String ident) {
-		TreeMap<Double,Double> result = history.get(ident);
-		if(result == null) {
-			result = new TreeMap<Double,Double>();
-			history.put(ident, result);
-		}
-		return result;
-	}
-
-	@Override
-	public Object getValue(int key) {
-		return valueTable[key];
-	}
-	
-	@Override
-	public void put(int key, Object value) {
-		valueTable[key] = value;
-	}
-	
-	public void put(String key, Object value) {
-		named.put(key, value);
-	}
-
-	public void setSize(int size) {
-		this.size = size;
-	}
-	
-	@Override
-	public int offset() {
-		return size;
-	}
-	
-	@Override
-	public ISystem getSystem() {
-		return this;
-	}
-	
-	@Override
-	public boolean initial() {
-		return initial;
-	}
-	
-	public Object evaluateFunction(IEnvironment environment, String name, ArgumentList args) {
-		return model.evaluateFunction(environment, name, args);
-	}
-	
-	@Override
-	public double time() {
-		return time;
-	}
-
-	double[] valueArray;
-	int[] valueIndices;
-	
-	public void addIndexed(int dimensions[], ArrayList<String> keys, String prefix, int d) {
-
-		if(d == dimensions.length) {
-			keys.add(prefix);
-			return;
-		}
-
-		String prefix2 = prefix;
-		if(d== 0) prefix2 += "[";
-		if(d>0) prefix2 += ",";
-
-		for(int i=0;i<dimensions[d];i++) {
-			String prefix3 = prefix2 + (i+1);
-			if(d+1 == dimensions.length) prefix3 += "]";
-			addIndexed(dimensions, keys, prefix3, d+1);
-		}
-		
-	}
-	
-	public int length(int[] dimension) {
-		int result = 1;
-		for(int d : dimension) result *=d;
-		return result;
-	}
-	
-	public void addVariable(String name, int index, int[] dimensions, ArrayList<String> keys, TIntArrayList indices, Set<String> used) {
-
-		if(!used.add(name)) return;
-		
-		if(dimensions == null) {
-			keys.add(name);
-			indices.add(index);
-		} else {
-			addIndexed(dimensions, keys, name, 0);
-			for(int i=0;i<length(dimensions);i++)
-				indices.add(index+i);
-		}
-
-	}
-	
-	public void addVariable(Variable var, ArrayList<String> keys, TIntArrayList indices, Set<String> used) {
-		addVariable(var.base.name, var.base.index, var.base.dimensions, keys, indices, used);
-	}
-
-	public String[] getValueKeyArray() {
-		
-		ArrayList<String> keys = new ArrayList<String>();
-		TIntArrayList indices = new TIntArrayList();
-		Set<String> used = new HashSet<String>();
-		
-		for (int i = 0; i < model.assignmentArray.length; i++) {
-			addVariable(model.assignmentArray[i].target, keys, indices, used);
-		}
-		
-		for (int i = 0; i < model.derivativeArray.length; i++) {
-			addVariable(model.derivativeArray[i].target, keys, indices, used);
-		}
-		
-		// NOTE: there is room for optimization as parameter values that do not
-		// change should only be obtained once (and parameter values that do
-		// change are (possibly) included in assignments or derivatives)
-		for(int i = 0; i < model.parameterArray.length; i++) {
-			addVariable(model.parameterArray[i].variable, keys, indices, used);
-		}
-		
-		for(Map.Entry<String,VariableBase> entry : model.copies.entrySet()) {
-			addVariable(entry.getKey(), entry.getValue().index, entry.getValue().dimensions, keys, indices, used);
-		}
-		
-		valueArray = new double[keys.size()];
-		
-		keyIndexMap.clear();
-		for(int i=0;i<keys.size();i++) {
-			String key = keys.get(i);
-			int index = indices.get(i);
-			keyIndexMap.put(key, index);
-		}
-		
-		valueIndices = new int[keys.size()];
-		getValueIndices();
-		
-		return keys.toArray(new String[keys.size()]);
-		
-	}
-	
-	public int[] getValueIndices() {
-
-		int offset = 0;
-
-		Set<String> used = new HashSet<String>();
-
-		for (int i = 0; i < model.assignmentArray.length; i++) {
-			Variable v = model.assignmentArray[i].target;
-			if(!used.add(v.base.name)) continue;
-			for(int index=0;index<v.base.dimension();index++)
-				valueIndices[offset++] = v.base.index(this, null)+index;
-		}
-		
-		for (int i = 0; i < model.derivativeArray.length; i++) {
-			Variable v = model.derivativeArray[i].target;
-			if(!used.add(v.base.name)) continue;
-			for(int index=0;index<v.base.dimension();index++) {
-				valueIndices[offset++] = v.base.index(this, null)+index;
-			}
-		}
-		
-		// NOTE: there is room for optimization as parameter values that do not
-		// change should only be obtained once (and parameter values that do
-		// change are (possibly) included in assignments or derivatives)
-		for(int i = 0; i < model.parameterArray.length; i++) {
-			Variable v = model.parameterArray[i].variable;
-			if(!used.add(v.base.name)) continue;
-			for(int index=0;index<v.base.dimension();index++)
-				valueIndices[offset++] = v.base.index(this, null)+index;
-		}
-
-		for(Map.Entry<String,VariableBase> entry : model.copies.entrySet()) {
-			VariableBase base = entry.getValue();
-			if(!used.add(entry.getKey())) continue;
-			for(int index=0;index<base.dimension();index++)
-				valueIndices[offset++] = base.index(this, null)+index;
-		}
-		
-		return valueIndices;
-		
-	}
-
-	// TODO: this is probably not smart at all, figure out a better way to obtain results
-	public double[] getValueArray() {
-
-		for(int i=0;i<valueArray.length;i++) {
-			Double value = (Double)getValue(valueIndices[i]);
-			// FIXME: should not be fixed like this
-			if(value == null) value = 0.0;
-			valueArray[i] = value;
-		}
-		
-		return valueArray;
-		
-//		int offset = 0;
-//
-//		Set<String> used = new HashSet<String>();
-//
-//		for (int i = 0; i < model.assignmentArray.length; i++) {
-//			Variable v = model.assignmentArray[i].target;
-//			if(!used.add(v.base.name)) continue;
-//			for(int index=0;index<v.base.dimension();index++)
-//				valueArray[offset++] = (Double)getValue(v.base.index(this, null)+index);
-//		}
-//		
-//		for (int i = 0; i < model.derivativeArray.length; i++) {
-//			Variable v = model.derivativeArray[i].target;
-//			if(!used.add(v.base.name)) continue;
-//			for(int index=0;index<v.base.dimension();index++) {
-//				Double value = (Double)getValue(v.base.index(this, null)+index);
-//				// FIXME: should not be fixed like this
-//				if(value == null) value = 0.0;
-//				valueArray[offset++] = value;
-//			}
-//		}
-//		
-//		// NOTE: there is room for optimization as parameter values that do not
-//		// change should only be obtained once (and parameter values that do
-//		// change are (possibly) included in assignments or derivatives)
-//		for(int i = 0; i < model.parameterArray.length; i++) {
-//			Variable v = model.parameterArray[i].variable;
-//			if(!used.add(v.base.name)) continue;
-//			for(int index=0;index<v.base.dimension();index++)
-//				valueArray[offset++] = (Double)getValue(v.base.index(this, null)+index);
-//		}
-//
-//		for(Map.Entry<String,VariableBase> entry : model.copies.entrySet()) {
-//			VariableBase base = entry.getValue();
-//			if(!used.add(entry.getKey())) continue;
-//			for(int index=0;index<base.dimension();index++)
-//				valueArray[offset++] = (Double)getValue(base.index(this, null)+index);
-//		}
-//		
-//		return valueArray;
-		
-	}
-
-	@Override
-	public Object getNamedValue(String key) {
-		return named.get(key);
-	}
-
-	public void setValue(String key, double value) {
-		int index = keyIndexMap.get(key);
-		put(index, value);
-	}
-	
-	public void setAssigned(Object ass) {
-		assigned.add(ass);
-	}
-	
-	public boolean isAssigned(Object o) {
-		return assigned.contains(o);
-	}
-	
-	private Set<Object> assigned = new HashSet<Object>();
-
-}
+/*******************************************************************************
+ * Copyright (c) 2013 Semantum Oy.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Semantum Oy - initial API and implementation
+ *     VTT Technical Research Centre of Finland - #4488
+ *******************************************************************************/
+package fi.semantum.sysdyn.solver;
+
+import fi.semantum.sysdyn.solver.Array.Modifier;
+import gnu.trove.list.array.TIntArrayList;
+import gnu.trove.map.hash.TObjectIntHashMap;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+import java.util.TreeMap;
+
+interface Fn {
+	public Object evaluate(IEnvironment environment, int argc);
+	public Object evaluateInput(IEnvironment environment, int argPosition);
+	public void setLocals(IEnvironment environment);
+	public int offset();
+	public Variable[] parameters(int args);
+}
+
+abstract class Fn1 implements Fn {
+
+	Variable[] parameters;
+	
+	public Fn1(int pCount) {
+		if(pCount > 0) {
+			parameters = new Variable[pCount];
+			for(int i=0;i<pCount;i++)
+				parameters[i] = new Variable(new VariableBase("", i));
+		}
+	}
+	
+	public int offset() {
+		return 0;
+	}
+	
+	public Variable[] parameters(int argc) {
+		if(parameters != null) return parameters;
+		else {
+			Variable[] ret = new Variable[argc];
+			for(int i=0;i<argc;i++)
+				ret[i] = new Variable(new VariableBase("", i));
+			return ret;
+		}
+	}
+	
+	@Override
+	public void setLocals(IEnvironment environment) {
+	}
+	
+	@Override
+	public Object evaluateInput(IEnvironment environment, int argPosition) {
+		// Function frame size is constant - this is called when padding is needed
+		return null;
+	}
+	
+}
+
+abstract class FnRandom extends Fn1 {
+	
+	protected Random random = null;
+
+	public FnRandom(int pCount) {
+		super(pCount);
+	}
+	
+}
+
+final public class Environment implements IEnvironment, ISystem {
+	
+	final Map<String,Object> named = new HashMap<String,Object>();
+
+	public Model model;
+	public double step;
+	public double time;
+	public boolean initial = true;
+	public int size;
+	
+	public Object[] valueTable;
+	
+	public TObjectIntHashMap<String> keyIndexMap = new TObjectIntHashMap<String>(); 
+
+	HashMap<String,TreeMap<Double,Double>> history = new HashMap<String,TreeMap<Double,Double>>();
+
+	public Environment(Model model, double step, double start) {
+		this.model = model;
+		this.step = step;
+		this.time = start;
+		
+		model.functions.put("sin", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.sin(x);
+			}
+			
+		});
+		model.functions.put("cos", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.cos(x);
+			}
+			
+		});
+		model.functions.put("tan", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.tan(x);
+			}
+			
+		});
+		model.functions.put("asin", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.asin(x);
+			}
+			
+		});
+		model.functions.put("acos", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.acos(x);
+			}
+			
+		});
+		model.functions.put("atan", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.atan(x);
+			}
+			
+		});
+		model.functions.put("toRadians", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.toRadians(x);
+			}
+			
+		});
+		model.functions.put("toDegrees", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.toDegrees(x);
+			}
+			
+		});
+		model.functions.put("exp", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.exp(x);
+			}
+			
+		});
+		model.functions.put("log", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.log(x);
+			}
+			
+		});
+		model.functions.put("log10", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.log10(x);
+			}
+			
+		});
+		model.functions.put("sqrt", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.sqrt(x);
+			}
+			
+		});
+		model.functions.put("cbrt", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.cbrt(x);
+			}
+			
+		});
+		model.functions.put("mod", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Double y = (Double)environment.getValue(1);
+				return mod(x, y);
+			}
+
+			double mod(double x, double y) {
+				return x - Math.floor(x/y)*y;
+			}
+
+		});
+		model.functions.put("rem", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Double y = (Double)environment.getValue(1);
+				return Math.IEEEremainder(x, y);
+			}
+
+		});
+		model.functions.put("ceil", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object value = environment.getValue(0);
+				if(value instanceof Double) {
+					return Math.ceil((Double)value);
+				} else if(value instanceof Array) {
+					return ((Array)value).copy(new Modifier() {
+
+						@Override
+						public Object modify(Object o) {
+							if(o instanceof Double) {
+								return Math.ceil((Double)o);
+							} else {
+								throw new IllegalStateException();
+							}
+						}
+						
+					});
+				} else {
+					throw new IllegalStateException();
+				}
+			}
+			
+		});
+		model.functions.put("floor", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object value = environment.getValue(0);
+				if(value instanceof Double) {
+					return Math.floor((Double)value);
+				} else if(value instanceof Array) {
+					return ((Array)value).copy(new Modifier() {
+
+						@Override
+						public Object modify(Object o) {
+							if(o instanceof Double) {
+								return Math.floor((Double)o);
+							} else {
+								throw new IllegalStateException();
+							}
+						}
+						
+					});
+				} else {
+					throw new IllegalStateException();
+				}
+			}
+			
+		});
+		model.functions.put("rint", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.rint(x);
+			}
+			
+		});
+		model.functions.put("atan2", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Double y = (Double)environment.getValue(1);
+				return Math.atan2(x, y);
+			}
+			
+		});
+		model.functions.put("pow", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Double y = (Double)environment.getValue(1);
+				return Math.pow(x, y);
+			}
+			
+		});
+		model.functions.put("round", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				long result = Math.round(x); 
+				return (int)result;
+			}
+			
+		});
+
+		model.functions.put("abs", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object o = environment.getValue(0);
+				if(o instanceof Double) {
+					return Math.abs((Double)o);
+				} else if (o instanceof Integer) {
+					return Math.abs((Integer)o);
+				} else {
+					throw new IllegalStateException("Unsupported argument to abs: " + o);
+				}
+			}
+			
+		});
+
+		model.functions.put("min", new Fn1(5) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object first = environment.getValue(0);
+				if(first instanceof Double) {
+					Double result = (Double)first;
+					for(int i=1;i<argc;i++) {
+						Double d = (Double)environment.getValue(i);
+						if(d < result) result = d;
+					}
+					return result;
+				} else if (first instanceof Integer) {
+					Integer result = (Integer )first;
+					for(int i=1;i<argc;i++) {
+						Integer  d = (Integer )environment.getValue(i);
+						if(d < result) result = d;
+					}
+					return result;
+				} else {
+					throw new IllegalStateException("Unsupported argument to min: " + first);
+				}
+			}
+			
+		});
+		model.functions.put("max", new Fn1(5) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object first = environment.getValue(0);
+				if(first instanceof Double) {
+					Double result = (Double)first;
+					for(int i=1;i<argc;i++) {
+						Double d = (Double)environment.getValue(i);
+						if(d > result) result = d;
+					}
+					return result;
+				} else if (first instanceof Integer) {
+					Integer result = (Integer )first;
+					for(int i=1;i<argc;i++) {
+						Integer  d = (Integer )environment.getValue(i);
+						if(d > result) result = d;
+					}
+					return result;
+				} else {
+					throw new IllegalStateException("Unsupported argument to max: " + first);
+				}
+			}
+			
+		});
+
+		model.functions.put("ulp", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.ulp(x);
+			}
+			
+		});
+
+		model.functions.put("signum", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.signum(x);
+			}
+			
+		});
+
+		model.functions.put("sinh", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.sinh(x);
+			}
+			
+		});
+
+		model.functions.put("cosh", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.cosh(x);
+			}
+			
+		});
+		
+		model.functions.put("cross", new Fn1(2) {
+
+			//Returns index 0 with input 1 as a Double
+			//index 1 with input 2 as a Double, etc.
+			private Double get(Array a, int crossIndex) {
+				return (Double)a.element(crossIndex - 1);
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Array X = (Array)environment.getValue(0);
+				Array Y = (Array)environment.getValue(1);
+				if(X.dimension() != 3 && Y.dimension() != 3) {
+					return null;
+				} else {
+					Array result = new Array(3);
+					Double a = (get( X,2 )*get( Y,3 )) - (get( X,3 )*get( Y,2 ));
+					Double b = (get( X,3 )*get( Y,1 )) - (get( X,1 )*get( Y,3 ));
+					Double c = (get( X,1 )*get( Y,2 )) - (get( X,2 )*get( Y,1 ));
+					result.addElement(a);
+					result.addElement(b);
+					result.addElement(c);
+					return result;
+				}
+			}
+			
+		});
+		model.functions.put("tanh", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.tanh(x);
+			}
+			
+		});
+
+		model.functions.put("hypot", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Double y = (Double)environment.getValue(1);
+				return Math.hypot(x, y);
+			}
+			
+		});
+
+		model.functions.put("expm1", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.expm1(x);
+			}
+			
+		});
+
+		model.functions.put("log1p", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.log1p(x);
+			}
+			
+		});
+
+		model.functions.put("copySign", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Double y = (Double)environment.getValue(1);
+				return Math.copySign(x, y);
+			}
+			
+		});
+
+		model.functions.put("getExponent", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.getExponent(x);
+			}
+			
+		});
+
+		model.functions.put("nextAfter", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Double y = (Double)environment.getValue(1);
+				return Math.nextAfter(x, y);
+			}
+			
+		});
+
+		model.functions.put("nextUp", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				return Math.nextUp(x);
+			}
+			
+		});
+
+		model.functions.put("scalb", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				Integer y = (Integer)environment.getValue(1);
+				return Math.scalb(x, y);
+			}
+			
+		});
+
+		model.functions.put("ndims", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Array array = (Array)environment.getValue(0);
+				return Double.valueOf(array.elements().size());
+			}
+			
+		});
+		
+		model.functions.put("diagonal", new Fn1(1) {
+			
+			private Array make(int[] dims, int pos) {
+				Array result = new Array();
+				int d = dims[pos];
+				if(pos == dims.length - 1) {
+					for(int i=0;i<d;i++) result.addElement(0.0);
+				} else {
+					for(int i=0;i<d;i++) result.addElement(make(dims, pos+1));
+				}
+				return result;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Array diagonalInputValues = (Array)environment.getValue(0);
+				int s = diagonalInputValues.dimension();
+				Array result = make(new int[] {s, s}, 0);
+				for(int i = 0; i < s; i++) {
+					Array sub = (Array)result.element(i);
+					sub.setElement(i, diagonalInputValues.element(i));
+					result.setElement(i, sub);
+				}
+				return result;
+			}
+		});
+		
+		model.functions.put("identity", new Fn1(1) {
+			
+			private Array make(int[] dims, int pos) {
+				Array result = new Array();
+				int d = dims[pos];
+				if(pos == dims.length - 1) {
+					for(int i=0;i<d;i++) result.addElement(0.0);
+				} else {
+					for(int i=0;i<d;i++) result.addElement(make(dims, pos+1));
+				}
+				return result;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double size = (Double)environment.getValue(0);
+				int s = size.intValue();
+				Array result = make(new int[] {s, s}, 0);
+				for(int i = 0; i < s; i++) {
+					Array sub = (Array)result.element(i);
+					sub.setElement(i, 1.0);
+					result.setElement(i, sub);
+				}
+				return result;
+			}
+		});
+		
+		model.functions.put("linspace", new Fn1(3){
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double startValue = (Double)environment.getValue(0);
+				Double endValue = (Double)environment.getValue(1);
+				Double n = (Double)environment.getValue(2);
+				
+				if(n <= 2) {
+					Array res = new Array(2);
+					res.addElement(startValue);
+					res.addElement(endValue);
+					return res;
+				}
+
+				Array result = new Array(n.intValue());
+				Double stepSize = (endValue - startValue) / (n - 1);
+				for(int i = 0; i < (n-1); i++) {
+					result.addElement(startValue + (stepSize*i));
+				}
+				result.addElement(endValue);
+				return result;
+			}
+			
+		});
+		
+		model.functions.put("size", new Fn1(-1){
+			
+			private List<Integer> findRecursive(Array array) {
+				int s = array.elements().size();
+				List<Integer> result = new ArrayList<>();
+				result.add(s);
+				if(s > 0) {
+					Object e = array.element(0);
+					if(e instanceof Array) {
+						List<Integer> found = findRecursive((Array)e);
+						result.addAll(found);
+					}
+				}
+				return result;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				if(argc==1) {
+					Array array = (Array)environment.getValue(0);
+					List<Integer> resultL = findRecursive(array);
+					Array result = new Array();
+					for(Integer i : resultL) {
+						result.addElement(i);
+					}
+					return result;
+				} else if(argc==2) {
+					Array array = (Array)environment.getValue(0);
+					Double col = (Double)environment.getValue(1);
+					return Double.valueOf(array.size(col.intValue()));
+				} else {
+					return null;
+				}
+			}
+			
+		});
+		
+		model.functions.put("zidz", new Fn1(2) {
+
+			private Object evaluate(Double p1, Double p2) {
+				if(Math.abs(p2) < 1e-12) return 0.0;
+				else return p1 / p2;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object o1 = environment.getValue(0);
+				Object o2 = environment.getValue(1);
+				
+				if(o1 instanceof Double && o2 instanceof Double) {
+					return evaluate((Double)o1, (Double)o2);
+				}
+				if(o1 instanceof Array && o2 instanceof Array) {
+					Array la = (Array)o1;
+					Array ra = (Array)o2;
+					Collection<Object> lae = la.elements();
+					Collection<Object> rae = ra.elements();
+					if(lae.size() != rae.size()) throw new UnsupportedOperationException();
+					Iterator<Object> li = lae.iterator();
+					Iterator<Object> ri = rae.iterator();
+					Array result = new Array();
+					for(int i=0;i<lae.size();i++) {
+						double ld = (Double)li.next();
+						double rd = (Double)ri.next();
+						result.addElement(evaluate(ld,rd));
+					}
+					return result;
+				}
+				throw new IllegalStateException();
+				
+				
+			}
+			
+		});
+		model.functions.put("xidz", new Fn1(3) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double p1 = (Double)environment.getValue(0);
+				Double p2 = (Double)environment.getValue(1);
+				Double x = (Double)environment.getValue(2);
+				if(Math.abs(p2) < 1e-12) return x;
+				else return p1 / p2;
+			}
+			
+		});
+		model.functions.put("availabilityExternal", new Fn1(4) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double numberOfDays = (Double)environment.getValue(0);
+				Double numberOfDesigners = (Double)environment.getValue(1);
+				@SuppressWarnings("unused")
+				Double rseed = (Double)environment.getValue(2);
+				@SuppressWarnings("unused")
+				Array availability = (Array)environment.getValue(3);
+				Array result = new Array();
+				for(int i=0;i<numberOfDays.intValue()*numberOfDesigners.intValue();i++) {
+					result.addElement(Math.random());
+				}
+				return result;
+			}
+			
+		});
+		model.functions.put("pre", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				
+				return (Double)environment.getValue(0);
+				
+			}
+			
+		});
+		model.functions.put("fill", new Fn1(3) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double value = (Double)environment.getValue(0);
+				Double dim1 = (Double)environment.getValue(1);
+				if(argc == 2) {
+					Array result = new Array();
+					for(int i=0;i<dim1.intValue();i++) {
+						result.addElement(value);
+					}
+					return result;
+				} else if(argc == 3) {
+					Double dim2 = (Double)environment.getValue(2);
+					Array result = new Array();
+					for(int i=0;i<dim1.intValue();i++) {
+						Array array = new Array();
+						for(int j=0;j<dim2.intValue();j++) {
+							array.addElement(value);
+						}
+						result.addElement(array);
+					}
+					return result;
+				} else throw new UnsupportedOperationException();
+			}
+			
+		});
+		model.functions.put("randomNumber", new FnRandom(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double seed = (Double)environment.getValue(0);
+				
+				if (random == null) {
+					random = new Random(Double.doubleToLongBits(seed));
+				}
+				
+				return random.nextDouble();
+			}
+			
+		});
+		model.functions.put("randomUniform", new FnRandom(4) {
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double min = (Double)environment.getValue(0);
+				Double max = (Double)environment.getValue(1);
+				Double seed = (Double)environment.getValue(2);
+				
+				// the fourth parameter should be "time" and is only necessary
+				// because sysdyn treats all functions as side-effect-free and
+				// does not evaluate a function "needlessly" if the parameters
+				// do not change. the parameter does not actually do anything
+				// though so we can safely ignore it here
+				
+				if (random == null) {
+					random = new Random(Double.doubleToLongBits(seed));
+				}
+				return random.nextDouble() * (max - min) + min;
+			}
+			
+		});
+		model.functions.put("randomNormal", new FnRandom(6) {
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double min = (Double)environment.getValue(0);
+				Double max = (Double)environment.getValue(1);
+				Double mean = (Double)environment.getValue(2);
+				Double stdev = (Double)environment.getValue(3);
+				Double seed = (Double)environment.getValue(4);
+				
+				if (random == null) {
+					random = new Random(Double.doubleToLongBits(seed));
+				}
+				
+				// TODO: use an actual library for this stuff
+				
+				return NormalDistribution.uniformVariableToNormal(min, max, mean, stdev, random.nextDouble());
+			}
+			
+		});
+		model.functions.put("initial", new Fn1(0) {
+
+			@Override
+			public Object evaluate(IEnvironment _environment, int argc) {
+				return _environment.getSystem().initial();
+			}
+			
+		});
+		model.functions.put("noEvent", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				
+				return environment.getValue(0);
+				
+			}
+			
+		});
+		model.functions.put("integer", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object value = environment.getValue(0);
+				if(value instanceof Double) {
+					double d = ((Double)value).intValue(); 
+					return d;
+				} else if(value instanceof Array) {
+					return ((Array)value).copy(new Modifier() {
+
+						@Override
+						public Object modify(Object o) {
+							if(o instanceof Double) {
+								double d = ((Double)o).intValue(); 
+								return d;
+							} else {
+								throw new IllegalStateException();
+							}
+						}
+						
+					});
+				} else {
+					throw new IllegalStateException();
+				}
+			}
+			
+		});
+		model.functions.put("sum", new Fn1(1) {
+
+			public double sum(Array a) {
+				double res = 0;
+				for(Object element : a.elements()) {
+					if(element instanceof Array) {
+						res += sum((Array)element);
+					} else if(element instanceof Double) {
+						res += (Double)element;
+					} else {
+						throw new IllegalStateException("Tried to sum a non-numerical array");
+					}
+				}
+				return res;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Object value = environment.getValue(0);
+				if(value instanceof Double) return (Double)value;
+				Array arr = (Array)value;
+				return sum(arr);
+			}
+			
+		});
+		
+		model.functions.put("product", new Fn1(1) {
+			
+			public Double productRecursive(Array a) {
+				List<Object> elements = a.elements();
+				Double result = 1.0;
+				if(elements.size() > 0) {
+					if(elements.get(0) instanceof Array) {
+						for(Object e : elements) {
+							result = result * productRecursive((Array)e);
+						}
+					} else {
+						for(Object e : elements) {
+							result = result * (Double)e;
+						}
+					}
+				}
+				return result;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Array array = (Array)environment.getValue(0);
+				Double result = productRecursive(array);
+				return result;
+			}
+		});
+		
+		model.functions.put("ones", new Fn1(-1) {
+
+			private Array make(int[] dims, int pos) {
+				Array result = new Array();
+				int d = dims[pos];
+				if(pos == dims.length - 1) {
+					for(int i=0;i<d;i++) result.addElement(1.0);
+				} else {
+					for(int i=0;i<d;i++) result.addElement(make(dims, pos+1));
+				}
+				return result;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				int[] dims = new int[argc];
+				for(int i=0;i<argc;i++) {
+					Double d = (Double)environment.getValue(i);
+					dims[i] = d.intValue();
+				}
+				return make(dims, 0);
+			}
+			
+		});
+		model.functions.put("zeros", new Fn1(-1) {
+
+			private Array make(int[] dims, int pos) {
+				Array result = new Array();
+				int d = dims[pos];
+				if(pos == dims.length - 1) {
+					for(int i=0;i<d;i++) result.addElement(0.0);
+				} else {
+					for(int i=0;i<d;i++) result.addElement(make(dims, pos+1));
+				}
+				return result;
+			}
+			
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				int[] dims = new int[argc];
+				for(int i=0;i<argc;i++) {
+					Double d = (Double)environment.getValue(i);
+					dims[i] = d.intValue();
+				}
+				return make(dims, 0);
+			}
+			
+		});
+		model.functions.put("transpose", new Fn1(1) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				
+				Array array = (Array)environment.getValue(0);
+				return array.transposed();
+				
+			}
+			
+		});
+		
+		model.functions.put("div", new Fn1(2) {
+
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				int x = ((Double)environment.getValue(0)).intValue();
+				int y = ((Double)environment.getValue(1)).intValue();
+				return (double)(x/y);
+			}
+			
+		});
+		
+		
+		model.functions.put("sign", new Fn1(1) {
+			@Override
+			public Object evaluate(IEnvironment environment, int argc) {
+				Double x = (Double)environment.getValue(0);
+				if (x > 0.0) return 1.0;
+				else if (x < 0.0) return -1.0;
+				else return 0.0;
+			}
+		});
+		
+		model.functions.put("delay", new Fn1(4) {
+			
+			@Override
+			public Object evaluate(IEnvironment _environment, int argc) {
+			
+				String ident = (String)_environment.getValue(0);
+				Double value = (Double)_environment.getValue(1);
+				Double p1 = (Double)_environment.getValue(2);
+				
+				ISystem system = _environment.getSystem();
+				
+				TreeMap<Double,Double> history = system.getHistory(ident);
+				double time = system.time();
+				
+				history.put(time, value);
+				
+				Double key = history.ceilingKey(time-p1);
+				
+				return history.get(key);
+				
+			}
+			
+		});		
+		model.functions.put("cat", new Fn1(10) {
+			
+			@Override
+			public Object evaluate(IEnvironment _environment, int argc) {
+			
+				Double dim = (Double)_environment.getValue(0);
+				
+				Array array = new Array();
+				for(int i=1;i<argc;i++) {
+					Object ar = _environment.getValue(i);
+					if (ar instanceof Array) {
+						Array a = (Array)ar;
+						for(Object o : a.elements())
+							array.addElement(o);
+					} else {
+						throw new IllegalStateException();
+					}
+				}
+				
+				return array;
+				
+			}
+			
+		});		
+	}
+	
+	public TreeMap<Double,Double> getHistory(String ident) {
+		TreeMap<Double,Double> result = history.get(ident);
+		if(result == null) {
+			result = new TreeMap<Double,Double>();
+			history.put(ident, result);
+		}
+		return result;
+	}
+
+	@Override
+	public Object getValue(int key) {
+		return valueTable[key];
+	}
+	
+	@Override
+	public void put(int key, Object value) {
+		valueTable[key] = value;
+	}
+	
+	public void put(String key, Object value) {
+		named.put(key, value);
+	}
+
+	public void setSize(int size) {
+		this.size = size;
+	}
+	
+	@Override
+	public int offset() {
+		return size;
+	}
+	
+	@Override
+	public ISystem getSystem() {
+		return this;
+	}
+	
+	@Override
+	public boolean initial() {
+		return initial;
+	}
+	
+	public Object evaluateFunction(IEnvironment environment, String name, ArgumentList args) {
+		return model.evaluateFunction(environment, name, args);
+	}
+	
+	@Override
+	public double time() {
+		return time;
+	}
+
+	double[] valueArray;
+	int[] valueIndices;
+	
+	public void addIndexed(int dimensions[], ArrayList<String> keys, String prefix, int d) {
+
+		if(d == dimensions.length) {
+			keys.add(prefix);
+			return;
+		}
+
+		String prefix2 = prefix;
+		if(d== 0) prefix2 += "[";
+		if(d>0) prefix2 += ",";
+
+		for(int i=0;i<dimensions[d];i++) {
+			String prefix3 = prefix2 + (i+1);
+			if(d+1 == dimensions.length) prefix3 += "]";
+			addIndexed(dimensions, keys, prefix3, d+1);
+		}
+		
+	}
+	
+	public int length(int[] dimension) {
+		int result = 1;
+		for(int d : dimension) result *=d;
+		return result;
+	}
+	
+	public void addVariable(String name, int index, int[] dimensions, ArrayList<String> keys, TIntArrayList indices, Set<String> used) {
+
+		if(!used.add(name)) return;
+		
+		if(dimensions == null) {
+			keys.add(name);
+			indices.add(index);
+		} else {
+			addIndexed(dimensions, keys, name, 0);
+			for(int i=0;i<length(dimensions);i++)
+				indices.add(index+i);
+		}
+
+	}
+	
+	public void addVariable(Variable var, ArrayList<String> keys, TIntArrayList indices, Set<String> used) {
+		addVariable(var.base.name, var.base.index, var.base.dimensions, keys, indices, used);
+	}
+
+	public String[] getValueKeyArray() {
+		
+		ArrayList<String> keys = new ArrayList<String>();
+		TIntArrayList indices = new TIntArrayList();
+		Set<String> used = new HashSet<String>();
+		
+		for (int i = 0; i < model.assignmentArray.length; i++) {
+			addVariable(model.assignmentArray[i].target, keys, indices, used);
+		}
+		
+		for (int i = 0; i < model.derivativeArray.length; i++) {
+			addVariable(model.derivativeArray[i].target, keys, indices, used);
+		}
+		
+		// NOTE: there is room for optimization as parameter values that do not
+		// change should only be obtained once (and parameter values that do
+		// change are (possibly) included in assignments or derivatives)
+		for(int i = 0; i < model.parameterArray.length; i++) {
+			addVariable(model.parameterArray[i].variable, keys, indices, used);
+		}
+		
+		for(Map.Entry<String,VariableBase> entry : model.copies.entrySet()) {
+			addVariable(entry.getKey(), entry.getValue().index, entry.getValue().dimensions, keys, indices, used);
+		}
+		
+		valueArray = new double[keys.size()];
+		
+		keyIndexMap.clear();
+		for(int i=0;i<keys.size();i++) {
+			String key = keys.get(i);
+			int index = indices.get(i);
+			keyIndexMap.put(key, index);
+		}
+		
+		valueIndices = new int[keys.size()];
+		getValueIndices();
+		
+		return keys.toArray(new String[keys.size()]);
+		
+	}
+	
+	public int[] getValueIndices() {
+
+		int offset = 0;
+
+		Set<String> used = new HashSet<String>();
+
+		for (int i = 0; i < model.assignmentArray.length; i++) {
+			Variable v = model.assignmentArray[i].target;
+			if(!used.add(v.base.name)) continue;
+			for(int index=0;index<v.base.dimension();index++)
+				valueIndices[offset++] = v.base.index(this, null)+index;
+		}
+		
+		for (int i = 0; i < model.derivativeArray.length; i++) {
+			Variable v = model.derivativeArray[i].target;
+			if(!used.add(v.base.name)) continue;
+			for(int index=0;index<v.base.dimension();index++) {
+				valueIndices[offset++] = v.base.index(this, null)+index;
+			}
+		}
+		
+		// NOTE: there is room for optimization as parameter values that do not
+		// change should only be obtained once (and parameter values that do
+		// change are (possibly) included in assignments or derivatives)
+		for(int i = 0; i < model.parameterArray.length; i++) {
+			Variable v = model.parameterArray[i].variable;
+			if(!used.add(v.base.name)) continue;
+			for(int index=0;index<v.base.dimension();index++)
+				valueIndices[offset++] = v.base.index(this, null)+index;
+		}
+
+		for(Map.Entry<String,VariableBase> entry : model.copies.entrySet()) {
+			VariableBase base = entry.getValue();
+			if(!used.add(entry.getKey())) continue;
+			for(int index=0;index<base.dimension();index++)
+				valueIndices[offset++] = base.index(this, null)+index;
+		}
+		
+		return valueIndices;
+		
+	}
+
+	// TODO: this is probably not smart at all, figure out a better way to obtain results
+	public double[] getValueArray() {
+
+		for(int i=0;i<valueArray.length;i++) {
+			Double value = (Double)getValue(valueIndices[i]);
+			// FIXME: should not be fixed like this
+			if(value == null) value = 0.0;
+			valueArray[i] = value;
+		}
+		
+		return valueArray;
+		
+//		int offset = 0;
+//
+//		Set<String> used = new HashSet<String>();
+//
+//		for (int i = 0; i < model.assignmentArray.length; i++) {
+//			Variable v = model.assignmentArray[i].target;
+//			if(!used.add(v.base.name)) continue;
+//			for(int index=0;index<v.base.dimension();index++)
+//				valueArray[offset++] = (Double)getValue(v.base.index(this, null)+index);
+//		}
+//		
+//		for (int i = 0; i < model.derivativeArray.length; i++) {
+//			Variable v = model.derivativeArray[i].target;
+//			if(!used.add(v.base.name)) continue;
+//			for(int index=0;index<v.base.dimension();index++) {
+//				Double value = (Double)getValue(v.base.index(this, null)+index);
+//				// FIXME: should not be fixed like this
+//				if(value == null) value = 0.0;
+//				valueArray[offset++] = value;
+//			}
+//		}
+//		
+//		// NOTE: there is room for optimization as parameter values that do not
+//		// change should only be obtained once (and parameter values that do
+//		// change are (possibly) included in assignments or derivatives)
+//		for(int i = 0; i < model.parameterArray.length; i++) {
+//			Variable v = model.parameterArray[i].variable;
+//			if(!used.add(v.base.name)) continue;
+//			for(int index=0;index<v.base.dimension();index++)
+//				valueArray[offset++] = (Double)getValue(v.base.index(this, null)+index);
+//		}
+//
+//		for(Map.Entry<String,VariableBase> entry : model.copies.entrySet()) {
+//			VariableBase base = entry.getValue();
+//			if(!used.add(entry.getKey())) continue;
+//			for(int index=0;index<base.dimension();index++)
+//				valueArray[offset++] = (Double)getValue(base.index(this, null)+index);
+//		}
+//		
+//		return valueArray;
+		
+	}
+
+	@Override
+	public Object getNamedValue(String key) {
+		return named.get(key);
+	}
+
+	public void setValue(String key, double value) {
+		int index = keyIndexMap.get(key);
+		put(index, value);
+	}
+	
+	public void setAssigned(Object ass) {
+		assigned.add(ass);
+	}
+	
+	public boolean isAssigned(Object o) {
+		return assigned.contains(o);
+	}
+	
+	private Set<Object> assigned = new HashSet<Object>();
+
+}
-- 
2.47.1