diff --git a/geo/Heading.h b/geo/Heading.h
index 172e124..ca2c293 100644
--- a/geo/Heading.h
+++ b/geo/Heading.h
@@ -64,13 +64,13 @@ public:
 
 	float getRAD() const {return rad;}
 
-	/** get a random heading */
-	static Heading rnd() {
-		static std::minstd_rand gen(1234);
-		static std::uniform_real_distribution<float> dist(0, _2PI);
-		const float rnd = dist(gen);
-		return Heading(rnd);
-	}
+//	/** get a random heading */
+//	static Heading rnd() {
+//		static std::minstd_rand gen(1234);
+//		static std::uniform_real_distribution<float> dist(0, _2PI);
+//		const float rnd = dist(gen);
+//		return Heading(rnd);
+//	}
 
 #undef _2PI
 
diff --git a/grid/walk/GridWalkPathControl.h b/grid/walk/GridWalkPathControl.h
index afae95c..7701af6 100644
--- a/grid/walk/GridWalkPathControl.h
+++ b/grid/walk/GridWalkPathControl.h
@@ -61,18 +61,22 @@ public:
 
 	}
 
+	Distribution::Normal<float> dHead = Distribution::Normal<float>(1, 0.01);
+	Distribution::Normal<float> dWalk = Distribution::Normal<float>(1, 0.10);
+	Distribution::Normal<float> sWalk = Distribution::Normal<float>(0, 0.15);
+
 	GridWalkState<T> getDestination(Grid<T>& grid, const GridWalkState<T>& start, float distance_m, float headChange_rad, Activity act) {
 
 		// proportional change of the heading
-        static 	Distribution::Normal<float> dHead(1, 0.01);
+		//static 	Distribution::Normal<float> dHead(1, 0.01);
 
 		// proportional change of the to-be-walked distance
-		static 	Distribution::Normal<float> dWalk(1, 0.10);
+		//static 	Distribution::Normal<float> dWalk(1, 0.10);
 
 		distance_m = distance_m*dWalk.draw()*1.4;		// TODO: why *2?
 		headChange_rad = headChange_rad*dHead.draw();
 
-		static 	Distribution::Normal<float> sWalk(0, 0.15);
+		//static 	Distribution::Normal<float> sWalk(0, 0.15);
 		if (distance_m == 0) { distance_m = std::abs( sWalk.draw() ); }
 
 		return walk(grid, start, distance_m, headChange_rad, act);
@@ -114,12 +118,14 @@ private:
 
 	}
 
+	Distribution::Uniform<float> dChange = Distribution::Uniform<float>(Angle::degToRad(0), +Angle::degToRad(359));
+
 	GridWalkState<T> walk(Grid<T>& grid, const GridWalkState<T>& start, const float distance_m, const float headChange_rad, Activity act) {
 
 		// try-again distribution
 		//static 	Distribution::Normal<float> dHead(0, Angle::degToRad(10));
 		//static 	Distribution::Normal<float> dUpdate(0, Angle::degToRad(3));
-			static	Distribution::Uniform<float> dChange(Angle::degToRad(0), +Angle::degToRad(359));
+		//	static	Distribution::Uniform<float> dChange(Angle::degToRad(0), +Angle::degToRad(359));
 
 		int retries = 5;
 		float walked_m = 0;
diff --git a/grid/walk/GridWalkSimpleControl.h b/grid/walk/GridWalkSimpleControl.h
index d5911ab..f736561 100644
--- a/grid/walk/GridWalkSimpleControl.h
+++ b/grid/walk/GridWalkSimpleControl.h
@@ -39,20 +39,22 @@ public:
 		gen.seed(1234);
 	}
 
-
+	Distribution::Normal<float> dHead = Distribution::Normal<float>(1, 0.01);
+	Distribution::Normal<float> dWalk = Distribution::Normal<float>(1, 0.10);
+	Distribution::Normal<float> sWalk = Distribution::Normal<float>(0, 0.10);
 
 	GridWalkState<T> getDestination(Grid<T>& grid, const GridWalkState<T>& start, float distance_m, float headChange_rad, Activity act) {
 
 		// proportional change of the heading
-		static 	Distribution::Normal<float> dHead(1, 0.01);
+
 
 		// proportional change of the to-be-walked distance
-		static 	Distribution::Normal<float> dWalk(1, 0.10);
+		//static 	Distribution::Normal<float> dWalk(1, 0.10);
 
 		distance_m = distance_m*dWalk.draw()*1.4;		// TODO: why * X?
 		headChange_rad = headChange_rad*dHead.draw();
 
-		static 	Distribution::Normal<float> sWalk(0, 0.10);
+		//static 	Distribution::Normal<float> sWalk(0, 0.10);
 		if (distance_m == 0) { distance_m = std::abs( sWalk.draw() ); }
 
 		return walk(grid, start, distance_m, headChange_rad);
@@ -90,12 +92,14 @@ private:
 
 	}
 
+	Distribution::Uniform<float> dChange = Distribution::Uniform<float>(Angle::degToRad(0), +Angle::degToRad(359));
+
 	GridWalkState<T> walk(Grid<T>& grid, const GridWalkState<T>& start, const float distance_m, const float headChange_rad) {
 
 		// try-again distribution
 		//static 	Distribution::Normal<float> dHead(0, Angle::degToRad(10));
 		//static 	Distribution::Normal<float> dUpdate(0, Angle::degToRad(3));
-			static	Distribution::Uniform<float> dChange(Angle::degToRad(0), +Angle::degToRad(359));
+		//	static	Distribution::Uniform<float> dChange(Angle::degToRad(0), +Angle::degToRad(359));
 
 		int retries = 5;
 		float walked_m = 0;
diff --git a/math/Interpolator.h b/math/Interpolator.h
index 765a196..55ef39f 100644
--- a/math/Interpolator.h
+++ b/math/Interpolator.h
@@ -34,6 +34,12 @@ public:
 		entries.push_back(InterpolatorEntry(key, value));
 	}
 
+	/** get the smallest added key */
+	Key getMinKey() const {return entries.front().key;}
+
+	/** get the largest added key */
+	Key getMaxKey() const {return entries.back().key;}
+
 	/** get the interpolated value for the given key */
 	Value get(const Key key) const {