From 725b65e460925aeda3dc2c0f34132348e05caaad Mon Sep 17 00:00:00 2001
From: jkauttio <jkauttio@ac1ea38d-2e2b-0410-8846-a27921b304fc>
Date: Wed, 27 May 2015 11:01:18 +0000
Subject: [PATCH] Implement randomUniform and fix randomNumber in internal
 solver

refs #5878

git-svn-id: https://www.simantics.org/svn/simantics/sysdyn/trunk@31359 ac1ea38d-2e2b-0410-8846-a27921b304fc
---
 .../semantum/sysdyn/solver/Environment.java   | 44 ++++++++++++++++---
 1 file changed, 39 insertions(+), 5 deletions(-)

diff --git a/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java b/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java
index f4f5c294..0f6fc0d3 100644
--- a/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java
+++ b/fi.semantum.sysdyn.solver/src/fi/semantum/sysdyn/solver/Environment.java
@@ -21,6 +21,7 @@ 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;
 
@@ -70,6 +71,16 @@ abstract class Fn1 implements Fn {
 	
 }
 
+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>();
@@ -625,15 +636,38 @@ final public class Environment implements IEnvironment, ISystem {
 			}
 			
 		});
-		model.functions.put("randomNumber", new Fn1(2) {
+		model.functions.put("randomNumber", new FnRandom(2) {
 
 			@Override
 			public Object evaluate(IEnvironment environment, int argc) {
-				@SuppressWarnings("unused")
 				Double seed = (Double)environment.getValue(0);
-				@SuppressWarnings("unused")
-				Double time = (Double)environment.getValue(1);
-				return Math.random();
+				
+				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;
 			}
 			
 		});
-- 
2.47.1