math: Avoid unneeded extra allocations for fixed-size data structures.

[pspp] / src / math / trimmed-mean.c

diff --git a/src/math/trimmed-mean.c b/src/math/trimmed-mean.c
index da3d4240e5b232533de6c5c31073b53adda49f48..4840fd2d66e0375a6114e3585fc5795b9acf60d7 100644 (file)
--- a/src/math/trimmed-mean.c
+++ b/src/math/trimmed-mean.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2008 Free Software Foundation, Inc.
+   Copyright (C) 2008, 2009, 2011 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -15,45 +15,47 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
-#include "trimmed-mean.h"
-#include <math/order-stats.h>
 
-#include <gl/xalloc.h>
-#include <libpspp/assertion.h>
+#include "math/trimmed-mean.h"
+
 #include <math.h>
-#include <data/val-type.h>
 
+#include "data/val-type.h"
+#include "libpspp/assertion.h"
+#include "libpspp/cast.h"
+#include "math/order-stats.h"
+
+#include "gl/xalloc.h"
 
 static void
 acc (struct statistic *s, const struct ccase *cx UNUSED, double c, double cc, double y)
 {
-  struct trimmed_mean *tm = (struct trimmed_mean *) s;
-  struct order_stats *os = (struct order_stats *) s;
+  struct trimmed_mean *tm = UP_CAST (s, struct trimmed_mean, parent.parent);
+  struct order_stats *os = &tm->parent;
 
-  if ( cc > os->k[0].tc && cc < os->k[1].tc)
-      tm->sum += c * y;
+  if (cc > os->k[0].tc && cc <= os->k[1].tc)
+    tm->sum += c * y;
 
-  if ( tm->cyk1p1 == SYSMIS && cc >os->k[0].tc)
-      tm->cyk1p1 = c * y;
+  if (tm->cyk1p1 == SYSMIS && cc > os->k[0].tc)
+    tm->cyk1p1 = c * y;
 }
 
 static void
 destroy (struct statistic *s)
 {
-  struct order_stats *os = (struct order_stats *) s;
-  free (os->k);
-  free (s);
+  struct trimmed_mean *tm = UP_CAST (s, struct trimmed_mean, parent.parent);
+  free (tm);
 }
 
-struct statistic *
+struct trimmed_mean *
 trimmed_mean_create (double W, double tail)
 {
-  struct trimmed_mean *tm = xzalloc (sizeof (*tm));
-  struct order_stats *os = (struct order_stats *) tm;
-  struct statistic *stat = (struct statistic *) tm;
+  struct trimmed_mean *tm = XZALLOC (struct trimmed_mean);
+  struct order_stats *os = &tm->parent;
+  struct statistic *stat = &os->parent;
 
   os->n_k = 2;
-  os->k = xcalloc (sizeof (*os->k), 2);
+  os->k = tm->k;
 
   assert (tail >= 0);
   assert (tail <= 1);
@@ -68,7 +70,7 @@ trimmed_mean_create (double W, double tail)
   tm->w = W;
   tm->tail = tail;
 
-  return stat;
+  return tm;
 }
 
 
@@ -77,18 +79,13 @@ trimmed_mean_calculate (const struct trimmed_mean *tm)
 {
   const struct order_stats *os = (const struct order_stats *) tm;
 
-  assert (os->cc == tm->w);
-
   return
     (
-     (os->k[0].cc_p1 - os->k[0].tc) * os->k[0].y_p1
-     -
-     (os->k[1].cc - os->k[1].tc) * os->k[1].y_p1
+     (os->k[0].cc - os->k[0].tc) * os->k[0].y_p1
+     +
+      (tm->w - os->k[1].cc - os->k[0].tc) * os->k[1].y_p1
      +
-     tm->sum
-     -
-     tm->cyk1p1
-     )
-    /
-    ( (1.0 - 2 * tm->tail) * tm->w);
+      tm->sum
+)
+    / ((1.0 - tm->tail * 2) * tm->w);
 }