math: Make 'accumulate' a feature of order statistics, not all stats.

[pspp] / src / math / np.c

diff --git a/src/math/np.c b/src/math/np.c
index b631820903e6ebf4e41a536ebe7ea964924af918..d297168c5967110f050f7a04de850e3438d4d2d8 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
@@ -15,20 +15,21 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
-#include "np.h"
+
+#include "math/np.h"
 
 #include <gsl/gsl_cdf.h>
 #include <math.h>
 #include <stdlib.h>
 
-#include <data/case.h>
-#include <data/casewriter.h>
-#include <libpspp/compiler.h>
-#include <libpspp/cast.h>
-#include <libpspp/misc.h>
-#include <math/moments.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 "xalloc.h"
+#include "gl/xalloc.h"
 
 static void
 destroy (struct statistic *stat)
@@ -37,16 +38,14 @@ destroy (struct statistic *stat)
   free (np);
 }
 
-
 static void
 acc (struct statistic *s, const struct ccase *cx UNUSED,
      double c, double cc, double y)
 {
-  struct ccase *cp;
   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;
 
@@ -61,43 +60,53 @@ acc (struct statistic *s, const struct ccase *cx UNUSED,
   maximize (&np->y_max, y);
   minimize (&np->y_min, y);
 
-  cp = case_create (casewriter_get_proto (np->writer));
-  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;
+  struct ccase *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 np *
-np_create (const struct moments1 *m)
-{
-  double variance;
-  struct np *np = xzalloc (sizeof (*np));
-  struct order_stats *os = &np->parent;
-  struct statistic *stat = &os->parent;
-  struct caseproto *proto;
-  int i;
-
-  np->prev_cc = 0;
+/* 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().
 
-  moments1_calculate (m, &np->n, &np->mean, &variance, NULL, NULL);
+   There is no function to produce the results, which appear in "struct np" for
+   passing directly to np_plot_create() or dnp_plot_create().
 
-  np->stddev = sqrt (variance);
-
-  np->y_min = np->ns_min = np->dns_min = DBL_MAX;
-  np->y_max = np->ns_max = np->dns_max = -DBL_MAX;
-
-  proto = caseproto_create ();
-  for (i = 0; i < n_NP_IDX; i++)
+   The caller must eventually destroy the returned structure, with
+   statistic_destroy(). */
+struct np *
+np_create (double n, double mean, double var)
+{
+  struct caseproto *proto = caseproto_create ();
+  for (size_t i = 0; i < n_NP_IDX; i++)
     proto = caseproto_add_width (proto, 0);
-  np->writer = autopaging_writer_create (proto);
+  struct casewriter *writer = autopaging_writer_create (proto);
   caseproto_unref (proto);
 
-  os->k = 0;
-  stat->destroy = destroy;
-  stat->accumulate = acc;
-
+  struct np *np = xmalloc (sizeof *np);
+  *np = (struct np) {
+    .parent = {
+      .parent = {
+        .destroy = destroy,
+      },
+      .accumulate = acc,
+    },
+    .n = n,
+    .mean = mean,
+    .stddev = sqrt (var),
+    .ns_min = DBL_MAX,
+    .ns_max = -DBL_MAX,
+    .dns_min = DBL_MAX,
+    .dns_max = -DBL_MAX,
+    .y_min = DBL_MAX,
+    .y_max = -DBL_MAX,
+    .writer = writer,
+  };
   return np;
 }