moments: Spell out "variance" ("var" is easily confused with "variable").

[pspp] / src / math / moments.c

diff --git a/src/math/moments.c b/src/math/moments.c
index a5be12e9cd0d53a108cd91ea98b3d85bd6daf4f3..c00d63650cb4540113caba2db52561b2da49237c 100644 (file)
--- a/src/math/moments.c
+++ b/src/math/moments.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 1997-9, 2000 Free Software Foundation, Inc.
+   Copyright (C) 1997-9, 2000, 2010, 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
@@ -15,17 +15,19 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
-#include "moments.h"
+
+#include "math/moments.h"
+
 #include <assert.h>
 #include <math.h>
 #include <stdlib.h>
-#include <libpspp/misc.h>
-#include <data/value.h>
 
-#include "xalloc.h"
+#include "data/val-type.h"
+#include "data/value.h"
+#include "libpspp/misc.h"
+
+#include "gl/xalloc.h"
 
-#include "gettext.h"
-#define _(msgid) gettext (msgid)
 \f
 /* Calculates variance, skewness, and kurtosis into *VARIANCE,
    *SKEWNESS, and *KURTOSIS if they are non-null and not greater
@@ -48,13 +50,13 @@ calc_moments (enum moment max_moment,
 
       /* From _SPSS Statistical Algorithms, 2nd ed.,
          0-918469-89-9, section "DESCRIPTIVES". */
-      if (fabs (*variance) >= 1e-20)
+      if (fabs (s2) >= 1e-20)
         {
           if (max_moment >= MOMENT_SKEWNESS && skewness != NULL && w > 2.)
             {
               double s3 = s2 * sqrt (s2);
               double g1 = (w * d3) / ((w - 1.0) * (w - 2.0) * s3);
-              if (finite (g1))
+              if (isfinite (g1))
                 *skewness = g1;
             }
           if (max_moment >= MOMENT_KURTOSIS && kurtosis != NULL && w > 3.)
@@ -62,7 +64,7 @@ calc_moments (enum moment max_moment,
               double den = (w - 2.) * (w - 3.) * pow2 (s2);
               double g2 = (w * (w + 1) * d4 / (w - 1.) / den
                            - 3. * pow2 (d2) / den);
-              if (finite (g2))
+              if (isfinite (g2))
                 *kurtosis = g2;
             }
         }
@@ -221,12 +223,8 @@ moments_calculate (const struct moments *m,
     }
   else
     {
-      /* After the second pass we can calculate any stat.  We
-         don't support "online" computation during the second
-         pass, so As a simple self-check, the total weight for
-         the passes must agree. */
+      /* After the second pass we can calculate any stat.  */
       assert (m->pass == 2);
-      assert (m->w1 == m->w2);
 
       if (m->w2 > 0.)
         {
@@ -457,6 +455,13 @@ moments1_destroy (struct moments1 *m)
   free (m);
 }
 \f
+
+double
+calc_semean (double variance, double W)
+{
+  return sqrt (variance / W);
+}
+
 /* Returns the standard error of the skewness for the given total
    weight W.