star-4v_s

commit c2d9d411adc7e599b1f9264730b0d28240bc8d01
parent 08665c66eacc289cde22f220bc464971c17d128f
Author: Christophe Coustet <christophe.coustet@meso-star.com>
Date:   Tue, 29 Mar 2016 14:12:57 +0200

BugFix in the standard error computation

Sum of x² was wrong

Diffstat:
M
src/s4vs.c
 | 
6
++----

1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/src/s4vs.c b/src/s4vs.c
@@ -57,7 +57,7 @@ realization(struct ssp_rng* rng, struct context* ctx)
 {
   struct s3d_attrib attrib;
   struct s3d_primitive prim;
-  double lambda, sum = 0, sum2 = 0;
+  double lambda, sum = 0;
   float normal[3], direction[4], origin[3], range[2], st[2];
   struct s3d_hit hit;
   int nfailures = 0;
@@ -107,11 +107,9 @@ realization(struct ssp_rng* rng, struct context* ctx)
     lambda = ssp_ran_exp(rng, ctx->ks);
     if(lambda >=  hit.distance) {
       sum += hit.distance;
-      sum2 += hit.distance * hit.distance;
       break;
     } else {
       sum += lambda;
-      sum2 += lambda * lambda;
       f3_add(origin, origin, f3_mulf(direction, direction, (float)lambda));
 
       do {
@@ -133,7 +131,7 @@ realization(struct ssp_rng* rng, struct context* ctx)
 #pragma omp atomic update
   ctx->sum += sum;
 #pragma omp atomic update
-  ctx->sum2 += sum2;
+  ctx->sum2 += sum * sum;
 #pragma omp atomic update
   ctx->nfailures += nfailures;
 }