Oops. Neglected to add new files.

[pspp] / src / math / extrema.c

diff --git a/src/math/extrema.c b/src/math/extrema.c
new file mode 100644 (file)
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+++ b/src/math/extrema.c
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+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2008 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
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+#include "extrema.h"
+#include <xalloc.h>
+#include <data/case.h>
+#include <data/val-type.h>
+#include <libpspp/compiler.h>
+#include <libpspp/ll.h>
+#include <stdlib.h>
+
+struct extrema
+{
+  size_t capacity;
+  size_t n;
+  struct ll_list list;
+
+  ll_compare_func *cmp_func;
+};
+
+
+static int
+cmp_descending (const struct ll *a_, const struct ll *b_, void *aux UNUSED)
+{
+  const struct extremum *a = ll_data (a_, struct extremum, ll);
+  const struct extremum *b = ll_data (b_, struct extremum, ll);
+
+  if ( a->value > b->value) return -1;
+
+  return (a->value < b->value);
+}
+
+static int
+cmp_ascending (const struct ll *a_, const struct ll *b_, void *aux UNUSED)
+{
+  const struct extremum *a = ll_data (a_, struct extremum, ll);
+  const struct extremum *b = ll_data (b_, struct extremum, ll);
+
+  if ( a->value < b->value) return -1;
+
+  return (a->value > b->value);
+}
+
+
+struct extrema *
+extrema_create (size_t n, enum extreme_end end)
+{
+  struct extrema *extrema = xzalloc (sizeof *extrema);
+  extrema->capacity = n;
+
+  if ( end == EXTREME_MAXIMA )
+    extrema->cmp_func = cmp_descending;
+  else
+    extrema->cmp_func = cmp_ascending;
+
+  ll_init (&extrema->list);
+
+  return extrema;
+}
+
+void
+extrema_destroy (struct extrema *extrema)
+{
+  struct ll *ll = ll_head (&extrema->list);
+
+  while (ll != ll_null (&extrema->list))
+    {
+      struct extremum *e = ll_data (ll, struct extremum, ll);
+
+      ll = ll_next (ll);
+      free (e);
+    }
+
+  free (extrema);
+}
+
+
+void
+extrema_add (struct extrema *extrema, double val,
+            double weight,
+            casenumber location)
+{
+  struct extremum *e = xzalloc (sizeof *e) ;
+  e->value = val;
+  e->location = location;
+  e->weight = weight;
+
+  if ( val == SYSMIS)
+    {
+      free (e);
+      return;
+    }
+
+  ll_insert_ordered (ll_head (&extrema->list), ll_null (&extrema->list),
+                      &e->ll,  extrema->cmp_func, NULL);
+
+  if ( extrema->n++ > extrema->capacity)
+    {
+      struct ll *tail = ll_tail (&extrema->list);
+      struct extremum *et = ll_data (tail, struct extremum, ll);
+
+      ll_remove (tail);
+
+      free (et);
+    }
+}
+
+
+const struct ll_list *
+extrema_list (const struct extrema *ex)
+{
+  return &ex->list;
+}
+
+
+bool
+extrema_top (const struct extrema *ex, double *v)
+{
+  const struct extremum  *top;
+
+  if ( ll_is_empty (&ex->list))
+    return false;
+
+  top = (const struct extremum *)
+    ll_data (ll_head(&ex->list), struct extremum, ll);
+
+  *v = top->value;
+
+  return true;
+}