1 files changed, 81 insertions, 0 deletions
diff --git a/gsl-1.9/cdf/fdist.c b/gsl-1.9/cdf/fdist.c
new file mode 100644
index 0000000..fb3321f
--- /dev/null
+++ b/gsl-1.9/cdf/fdist.c
@@ -0,0 +1,81 @@
+/* cdf/fdist.c
+ *
+ * Copyright (C) 2002 Przemyslaw Sliwa and Jason H. Stover.
+ * Copyright (C) 2006 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#include <config.h>
+#include <math.h>
+#include <gsl/gsl_cdf.h>
+#include <gsl/gsl_sf_gamma.h>
+#include <gsl/gsl_math.h>
+#include <gsl/gsl_errno.h>
+
+#include "error.h"
+#include "beta_inc.c"
+
+/*
+ * Lower tail.
+ */
+
+double
+gsl_cdf_fdist_P (const double x, const double nu1, const double nu2)
+{
+  double P;
+  double r = nu2 / nu1;
+
+  if (x < r)
+    {
+      double u = x / (r + x);
+
+      P = beta_inc_AXPY (1.0, 0.0, nu1 / 2.0, nu2 / 2.0, u);
+    }
+  else
+    {
+      double u = r / (r + x);
+
+      P = beta_inc_AXPY (-1.0, 1.0, nu2 / 2.0, nu1 / 2.0, u);
+    }
+
+  return P;
+}
+
+/*
+ * Upper tail.
+ */
+
+double
+gsl_cdf_fdist_Q (const double x, const double nu1, const double nu2)
+{
+  double Q;
+  double r = nu2 / nu1;
+
+  if (x < r)
+    {
+      double u = x / (r + x);
+
+      Q = beta_inc_AXPY (-1.0, 1.0, nu1 / 2.0, nu2 / 2.0, u);
+    }
+  else
+    {
+      double u = r / (r + x);
+
+      Q = beta_inc_AXPY (1.0, 0.0, nu2 / 2.0, nu1 / 2.0, u);
+    }
+
+  return Q;
+}