[Pspp-cvs] pspp/src/math ChangeLog moments.c

[Ben Pfaff]

CVSROOT:        /cvsroot/pspp
Module name:    pspp
Changes by:     Ben Pfaff <blp> 07/02/05 23:43:23

Modified files:
        src/math       : ChangeLog moments.c 

Log message:
        Reduce number of multiplications for higher moments.

CVSWeb URLs:
http://cvs.savannah.gnu.org/viewcvs/pspp/src/math/ChangeLog?cvsroot=pspp&r1=1.12&r2=1.13
http://cvs.savannah.gnu.org/viewcvs/pspp/src/math/moments.c?cvsroot=pspp&r1=1.4&r2=1.5

Patches:
Index: ChangeLog
===================================================================
RCS file: /cvsroot/pspp/pspp/src/math/ChangeLog,v
retrieving revision 1.12
retrieving revision 1.13
diff -u -b -r1.12 -r1.13
--- ChangeLog   7 Dec 2006 06:31:04 -0000       1.12
+++ ChangeLog   5 Feb 2007 23:43:23 -0000       1.13
@@ -1,3 +1,7 @@
+Mon Feb  5 15:42:14 2007  Ben Pfaff  <address@hidden>
+
+       * moments.c (moments_pass_two): Reduce number of multiplications.
+
 Thu Dec  7 15:27:49 WST 2006 John Darrington <address@hidden>
 
        * factor-stats.c factor-stats.h: Changed independent values to 

Index: moments.c
===================================================================
RCS file: /cvsroot/pspp/pspp/src/math/moments.c,v
retrieving revision 1.4
retrieving revision 1.5
diff -u -b -r1.4 -r1.5
--- moments.c   5 Feb 2007 21:15:18 -0000       1.4
+++ moments.c   5 Feb 2007 23:43:23 -0000       1.5
@@ -151,8 +151,6 @@
 void
 moments_pass_two (struct moments *m, double value, double weight) 
 {
-  double d, d_power;
-
   assert (m != NULL);
 
   if (m->pass == 1) 
@@ -164,28 +162,25 @@
 
   if (value != SYSMIS && weight >= 0.) 
     {
-      m->w2 += weight;
-
-      d = d_power = value - m->mean;
-      m->d1 += d_power * weight;
-
+      double d = value - m->mean;
+      double d1_delta = d * weight;
+      m->d1 += d1_delta;
       if (m->max_moment >= MOMENT_VARIANCE) 
         {
-          d_power *= d;
-          m->d2 += d_power * weight;
-
+          double d2_delta = d1_delta * d;
+          m->d2 += d2_delta;
           if (m->max_moment >= MOMENT_SKEWNESS)
             {
-              d_power *= d;
-              m->d3 += d_power * weight;
-
+              double d3_delta = d2_delta * d;
+              m->d3 += d3_delta;
               if (m->max_moment >= MOMENT_KURTOSIS)
                 {
-                  d_power *= d;
-                  m->d4 += d_power * weight;
+                  double d4_delta = d3_delta * d;
+                  m->d4 += d4_delta;
                 }
             }
         }
+      m->w2 += weight;
     }
 }