math: Improve comments.

[pspp] / src / math / np.c

diff --git a/src/math/np.c b/src/math/np.c
index 99584a5105b75879517e4b30982e9d78280a5dd1..220865ba3cbec59602ec9afccce2a6c193de813b 100644 (file)
--- a/src/math/np.c
+++ b/src/math/np.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2008, 2009 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
@@ -15,21 +15,27 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
-#include "np.h"
-#include <math/moments.h>
-#include <gl/xalloc.h>
-#include <stdlib.h>
-#include <math.h>
+
+#include "math/np.h"
+
 #include <gsl/gsl_cdf.h>
-#include <libpspp/compiler.h>
-#include <data/case.h>
-#include <data/casewriter.h>
+#include <math.h>
+#include <stdlib.h>
+
+#include "data/case.h"
+#include "data/casewriter.h"
+#include "libpspp/cast.h"
+#include "libpspp/compiler.h"
+#include "libpspp/misc.h"
+#include "math/moments.h"
+
+#include "gl/xalloc.h"
 
 static void
 destroy (struct statistic *stat)
 {
-  struct order_stats *os = (struct order_stats *) stat;
-  free (os);
+  struct np *np = UP_CAST (stat, struct np, parent.parent);
+  free (np);
 }
 
 
@@ -38,10 +44,10 @@ acc (struct statistic *s, const struct ccase *cx UNUSED,
      double c, double cc, double y)
 {
   struct ccase *cp;
-  struct np *np = (struct np *) s;
+  struct np *np = UP_CAST (s, struct np, parent.parent);
   double rank = np->prev_cc + (c + 1) / 2.0;
 
-  double ns = gsl_cdf_ugaussian_Pinv (rank / ( np->n + 1 ));
+  double ns = gsl_cdf_ugaussian_Pinv (rank / (np->n + 1));
 
   double z = (y - np->mean) / np->stddev;
 
@@ -56,37 +62,54 @@ acc (struct statistic *s, const struct ccase *cx UNUSED,
   maximize (&np->y_max, y);
   minimize (&np->y_min, y);
 
-  cp = case_create (n_NP_IDX);
-  case_data_rw_idx (cp, NP_IDX_Y)->f = y;
-  case_data_rw_idx (cp, NP_IDX_NS)->f = ns;
-  case_data_rw_idx (cp, NP_IDX_DNS)->f = dns;
+  cp = case_create (casewriter_get_proto (np->writer));
+  *case_num_rw_idx (cp, NP_IDX_Y) = y;
+  *case_num_rw_idx (cp, NP_IDX_NS) = ns;
+  *case_num_rw_idx (cp, NP_IDX_DNS) = dns;
   casewriter_write (np->writer, cp);
 
   np->prev_cc = cc;
 }
 
-struct order_stats *
-np_create (const struct moments1 *m)
+/* Creates and returns a data structure whose accumulated results can be used
+   to produce a normal probability plot.  The caller must supply the weighted
+   sample size N and the mean MEAN and variance VAR of the distribution, then
+   feed in the data with order_stats_accumulate() or
+   order_stats_accumulate_idx().
+
+   There is no function to produce the results, which appear in "struct np" for
+   passing directly to np_plot_create() or dnp_plot_create().
+
+   The caller must eventually destroy the returned structure, with
+   statistic_destroy(). */
+struct np *
+np_create (double n, double mean, double var)
 {
-  double variance;
-  struct np *np = xzalloc (sizeof (*np));
-  struct statistic *stat = (struct statistic *) np;
-  struct order_stats *os = (struct order_stats *) np;
+  struct np *np = XZALLOC (struct np);
+  struct order_stats *os = &np->parent;
+  struct statistic *stat = &os->parent;
+  struct caseproto *proto;
+  int i;
 
   np->prev_cc = 0;
 
-  moments1_calculate (m, &np->n, &np->mean, &variance, NULL, NULL);
+  np->n = n;
+  np->mean = mean;
 
-  np->stddev = sqrt (variance);
+  np->stddev = sqrt (var);
 
   np->y_min = np->ns_min = np->dns_min = DBL_MAX;
   np->y_max = np->ns_max = np->dns_max = -DBL_MAX;
 
-  np->writer = autopaging_writer_create (n_NP_IDX);
+  proto = caseproto_create ();
+  for (i = 0; i < n_NP_IDX; i++)
+    proto = caseproto_add_width (proto, 0);
+  np->writer = autopaging_writer_create (proto);
+  caseproto_unref (proto);
 
   os->k = 0;
   stat->destroy = destroy;
   stat->accumulate = acc;
 
-  return os;
+  return np;
 }