1 files changed, 89 insertions, 0 deletions
diff --git a/gsl-1.9/cdf/geometric.c b/gsl-1.9/cdf/geometric.c
new file mode 100644
index 0000000..1f671be
--- /dev/null
+++ b/gsl-1.9/cdf/geometric.c
@@ -0,0 +1,89 @@
+/* cdf/geometric.c
+ *
+ * Copyright (C) 2004 Jason H. Stover.
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#include <config.h>
+#include <math.h>
+#include <gsl/gsl_math.h>
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_cdf.h>
+
+#include "error.h"
+
+/* Pr (X <= k), i.e., the probability of n or fewer failures until the
+   first success. */
+
+double
+gsl_cdf_geometric_P (const unsigned int k, const double p)
+{
+  double P, a, q;
+
+  if (p > 1.0 || p < 0.0)
+    {
+      CDF_ERROR ("p < 0 or p > 1", GSL_EDOM);
+    }
+
+  if (k < 1)
+    {
+      return 0.0;
+    }
+
+  q = 1.0 - p;
+  a = (double) k;
+
+  if (p < 0.5)
+    {
+      P = -expm1 (a * log1p (-p));
+    }
+  else
+    {
+      P = 1.0 - pow (q, a);
+    }
+
+  return P;
+}
+
+double
+gsl_cdf_geometric_Q (const unsigned int k, const double p)
+{
+  double Q, a, q;
+
+  if (p > 1.0 || p < 0.0)
+    {
+      CDF_ERROR ("p < 0 or p > 1", GSL_EDOM);
+    }
+
+  if (k < 1)
+    {
+      Q = 1.0;
+    }
+
+  q = 1.0 - p;
+  a = (double) k;
+
+  if (p < 0.5)
+    {
+      Q = exp (a * log1p (-p));
+    }
+  else
+    {
+      Q = pow (q, a);
+    }
+
+  return Q;
+}