1 files changed, 153 insertions, 0 deletions
diff --git a/gsl-1.9/histogram/pdf.c b/gsl-1.9/histogram/pdf.c
new file mode 100644
index 0000000..78f9a22
--- /dev/null
+++ b/gsl-1.9/histogram/pdf.c
@@ -0,0 +1,153 @@
+/* histogram/pdf.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
+ * 
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <config.h>
+#include <stdlib.h>
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_histogram.h>
+
+#include "find.c"
+
+double
+gsl_histogram_pdf_sample (const gsl_histogram_pdf * p, double r)
+{
+  size_t i;
+  int status;
+
+/* Wrap the exclusive top of the bin down to the inclusive bottom of
+   the bin. Since this is a single point it should not affect the
+   distribution. */
+
+  if (r == 1.0)
+    {
+      r = 0.0;
+    }
+
+  status = find (p->n, p->sum, r, &i);
+
+  if (status)
+    {
+      GSL_ERROR_VAL ("cannot find r in cumulative pdf", GSL_EDOM, 0);
+    }
+  else
+    {
+      double delta = (r - p->sum[i]) / (p->sum[i + 1] - p->sum[i]);
+      double x = p->range[i] + delta * (p->range[i + 1] - p->range[i]);
+      return x;
+    }
+}
+
+gsl_histogram_pdf *
+gsl_histogram_pdf_alloc (const size_t n)
+{
+  gsl_histogram_pdf *p;
+
+  if (n == 0)
+    {
+      GSL_ERROR_VAL ("histogram pdf length n must be positive integer",
+                        GSL_EDOM, 0);
+    }
+
+  p = (gsl_histogram_pdf *) malloc (sizeof (gsl_histogram_pdf));
+
+  if (p == 0)
+    {
+      GSL_ERROR_VAL ("failed to allocate space for histogram pdf struct",
+                        GSL_ENOMEM, 0);
+    }
+
+  p->range = (double *) malloc ((n + 1) * sizeof (double));
+
+  if (p->range == 0)
+    {
+      free (p);         /* exception in constructor, avoid memory leak */
+
+      GSL_ERROR_VAL ("failed to allocate space for histogram pdf ranges",
+                        GSL_ENOMEM, 0);
+    }
+
+  p->sum = (double *) malloc ((n + 1) * sizeof (double));
+
+  if (p->sum == 0)
+    {
+      free (p->range);
+      free (p);         /* exception in constructor, avoid memory leak */
+
+      GSL_ERROR_VAL ("failed to allocate space for histogram pdf sums",
+                        GSL_ENOMEM, 0);
+    }
+
+  p->n = n;
+
+  return p;
+}
+
+int 
+gsl_histogram_pdf_init (gsl_histogram_pdf * p, const gsl_histogram * h)
+{
+  size_t i;
+  size_t n = p->n;
+
+  if (n != h->n)
+    {
+      GSL_ERROR ("histogram length must match pdf length", GSL_EINVAL);
+    }
+
+  for (i = 0; i < n; i++)
+    {
+      if (h->bin[i] < 0)
+        {
+          GSL_ERROR ("histogram bins must be non-negative to compute"
+                     "a probability distribution", GSL_EDOM);
+        }
+    }
+
+  for (i = 0; i < n + 1; i++)
+    {
+      p->range[i] = h->range[i];
+    }
+
+  {
+    double mean = 0, sum = 0;
+
+    for (i = 0; i < n; i++)
+      {
+        mean += (h->bin[i] - mean) / ((double) (i + 1));
+      }
+
+    p->sum[0] = 0;
+
+    for (i = 0; i < n; i++)
+      {
+        sum += (h->bin[i] / mean) / n;
+        p->sum[i + 1] = sum;
+      }
+  }
+
+  return GSL_SUCCESS;
+}
+
+
+void
+gsl_histogram_pdf_free (gsl_histogram_pdf * p)
+{
+  free (p->range);
+  free (p->sum);
+  free (p);
+}