1 files changed, 83 insertions, 0 deletions
diff --git a/gsl-1.9/cdf/nbinomial.c b/gsl-1.9/cdf/nbinomial.c
new file mode 100644
index 0000000..c2c17e7
--- /dev/null
+++ b/gsl-1.9/cdf/nbinomial.c
@@ -0,0 +1,83 @@
+/* cdf/negbinom.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) for a negative binomial random variable X, i.e.,
+ * the probability of k or fewer failuers before success n.
+ */
+
+double
+gsl_cdf_negative_binomial_P (const unsigned int k, const double p, const double n)
+{
+  double P;
+  double a;
+  double b;
+
+  if (p > 1.0 || p < 0.0)
+    {
+      CDF_ERROR ("p < 0 or p > 1", GSL_EDOM);
+    }
+
+  if (n < 0)
+    {
+      CDF_ERROR ("n < 0", GSL_EDOM);
+    }
+
+  a = (double) n;
+  b = (double) k + 1.0;
+  P = gsl_cdf_beta_P (p, a, b);
+
+  return P;
+}
+
+/*
+ * Pr ( X > k ).
+ */
+
+double
+gsl_cdf_negative_binomial_Q (const unsigned int k, const double p, const double n)
+{
+  double Q;
+  double a;
+  double b;
+
+  if (p > 1.0 || p < 0.0)
+    {
+      CDF_ERROR ("p < 0 or p > 1", GSL_EDOM);
+    }
+
+  if (n < 0)
+    {
+      CDF_ERROR ("n < 0", GSL_EDOM);
+    }
+
+  a = (double) n;
+  b = (double) k + 1.0;
+  Q = gsl_cdf_beta_Q (p, a, b);
+
+  return Q;
+}