[cig-commits] commit: Changed the distance functions in DVCWeights. The implementation of these functions using the StGermain dot products etc

[Mercurial]

changeset:   56:c1fc9c92ded2
user:        DavidMay
date:        Tue Dec 04 06:00:59 2007 +0000
files:       Weights/src/DVCWeights.c Weights/src/DVCWeights.h
description:
Changed the distance functions in DVCWeights. The implementation of these functions using the StGermain dot products etc
was extremely slow. These functions are now individually more than an order of magnitude faster.
For a test job in 3D with 80x80x80 cells and 40 particles per cell the result was an overall speed-up of more than 30%,
 i.e. a 2 hour run reduced to 1.5 hours.


diff -r ee509e232033 -r c1fc9c92ded2 Weights/src/DVCWeights.c
--- a/Weights/src/DVCWeights.c	Mon Nov 12 06:12:15 2007 +0000
+++ b/Weights/src/DVCWeights.c	Tue Dec 04 06:00:59 2007 +0000
@@ -289,7 +289,7 @@ void _DVCWeights_ClaimCells(struct chain
 void _DVCWeights_ClaimCells(struct chain **bbchain,struct cell **ccells,struct particle **pList,int p_i){
   int i,count;
   int cell_num0;
-  double x0,y0,x1,y1,x2,y2,z0,z1,z2,dist1,dist2;
+  double x0,y0,x1,y1,x2,y2,z0,z1,z2,dist1;
   struct chain *bchain = &(*bbchain)[p_i];
   struct cell *cells = *ccells;
   int *temp;
@@ -330,9 +330,8 @@ void _DVCWeights_ClaimCells(struct chain
 	y0 = cells[cell_num0].y;
 	z0 = cells[cell_num0].z;
 	
-	dist1 = _DVCWeights_DistanceSquared(x0,y0,z0,x1,y1,z1);
-	dist2 = _DVCWeights_DistanceSquared(x0,y0,z0,x2,y2,z2);
-	if(dist1 > dist2){
+	dist1 = _DVCWeights_DistanceTest(x0,y0,z0,x1,y1,z1,x2,y2,z2);
+	if(dist1 > 0.0){
 	  bchain->new_claimed_cells[count] = cell_num0;
 	  bchain->numclaimed++;
 	  count++;
@@ -348,7 +347,7 @@ void _DVCWeights_ClaimCells2D(struct cha
 void _DVCWeights_ClaimCells2D(struct chain **bbchain,struct cell2d **ccells,struct particle2d **pList,int p_i){
   int i,count;
   int cell_num0;
-  double x0,y0,x1,y1,x2,y2,dist1,dist2;
+  double x0,y0,x1,y1,x2,y2,dist1;
   struct chain *bchain = &(*bbchain)[p_i];
   struct cell2d *cells = *ccells;
   int *temp;
@@ -386,9 +385,8 @@ void _DVCWeights_ClaimCells2D(struct cha
 	x0 = cells[cell_num0].x;
 	y0 = cells[cell_num0].y;
 	
-	dist1 = _DVCWeights_DistanceSquared2D(x0,y0,x1,y1);
-	dist2 = _DVCWeights_DistanceSquared2D(x0,y0,x2,y2);
-	if(dist1 > dist2){
+	dist1 = _DVCWeights_DistanceTest2D(x0,y0,x1,y1,x2,y2);
+	if(dist1 > 0.0){
 	  bchain->new_claimed_cells[count] = cell_num0;
 	  bchain->numclaimed++;
 	  count++;
@@ -624,26 +622,19 @@ void _DVCWeights_ConstructGrid2D(struct 
 
 /** Calculate the sqaure of the distance between two points */
 double _DVCWeights_DistanceSquared(double x0, double y0, double z0, double x1, double y1, double z1){
-	double  position0[3], position1[3], vectorDistance[3];
-	double  dist;
-	Vec_SetScalar3D( position0, x0, y0, z0 );	
-	Vec_SetScalar3D( position1, x1, y1, z1 );
-	StGermain_VectorSubtraction( vectorDistance, position0, position1, 3 ) ;
-	dist = StGermain_VectorDotProduct(vectorDistance, vectorDistance, 3);
-	return dist;
+	return (x1-x0)*(x1-x0)+(y1-y0)*(y1-y0)+(z1-z0)*(z1-z0);
 }
 
 /** Calculate the sqaure of the distance between two points in 2D*/
 double _DVCWeights_DistanceSquared2D(double x0, double y0,double x1, double y1){
-	double  position0[2], position1[2], vectorDistance[2];
-	double dist;
-	Vec_SetScalar2D( position0, x0, y0);	
-	Vec_SetScalar2D( position1, x1, y1);
-	StGermain_VectorSubtraction( vectorDistance, position0, position1, 2 ) ;
-	dist = StGermain_VectorDotProduct(vectorDistance, vectorDistance, 2);
-	return dist;
-}
-
+	return (x1-x0)*(x1-x0)+(y1-y0)*(y1-y0);
+}
+double _DVCWeights_DistanceTest2D(double x0, double y0, double x1, double y1,double x2, double y2){
+        return (x1+x2-x0-x0)*(x1-x2) + (y1+y2-y0-y0)*(y1-y2);
+}
+double _DVCWeights_DistanceTest(double x0, double y0, double z0, double x1, double y1, double z1, double x2, double y2, double z2){
+        return (x1+x2-x0-x0)*(x1-x2) + (y1+y2-y0-y0)*(y1-y2) + (z1+z2-z0-z0)*(z1-z2);
+}
 /** Allocate the internal structs for the bchain (boundary chain) and the plist (particle list) */
 void _DVCWeights_InitialiseStructs( struct chain **bchain, struct particle **pList, int nump){
 
diff -r ee509e232033 -r c1fc9c92ded2 Weights/src/DVCWeights.h
--- a/Weights/src/DVCWeights.h	Mon Nov 12 06:12:15 2007 +0000
+++ b/Weights/src/DVCWeights.h	Tue Dec 04 06:00:59 2007 +0000
@@ -69,7 +69,7 @@
 
 	struct DVCWeights { __DVCWeights };
 	
-#define INC 50
+#define INC 150
 	
 struct cell{
   int p;/*particle index number*/
@@ -149,6 +149,9 @@ struct particle2d{
 	double _DVCWeights_DistanceSquared(
 				double x0, double y0, double z0, 
 				double x1, double y1, double z1);
+        double _DVCWeights_DistanceTest(double x0, double y0, double z0, 
+                                        double x1, double y1, double z1,
+                                        double x2, double y2, double z2);	
 	void   _DVCWeights_ConstructGrid(
 				struct cell **cell_list, 
 				int n, int m, int l,
@@ -187,6 +190,9 @@ struct particle2d{
 				int p_i);
 	void   _DVCWeights_ResetGrid2D(struct cell2d **cells, int n );
 	double _DVCWeights_DistanceSquared2D(double x0, double y0, double x1, double y1);
+	double _DVCWeights_DistanceTest2D(double x0, double y0,
+					  double x1, double y1,
+					  double x2, double y2);
 	void   _DVCWeights_ConstructGrid2D(
 				struct cell2d **cell_list, 
 				int m, int l,