1 files changed, 74 insertions, 0 deletions
diff --git a/gsl-1.9/specfunc/pow_int.c b/gsl-1.9/specfunc/pow_int.c
new file mode 100644
index 0000000..720b2e3
--- /dev/null
+++ b/gsl-1.9/specfunc/pow_int.c
@@ -0,0 +1,74 @@
+/* specfunc/pow_int.c
+ * 
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
+ * 
+ * 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.
+ */
+
+/* Author:  G. Jungman */
+
+#include <config.h>
+#include <gsl/gsl_math.h>
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_sf_pow_int.h>
+
+
+/*-*-*-*-*-*-*-*-*-*-*-* Functions w/ Error handling *-*-*-*-*-*-*-*-*-*-*-*/
+
+int gsl_sf_pow_int_e(double x, int n, gsl_sf_result * result)
+{
+  double value = 1.0;
+  int count = 0;
+
+  /* CHECK_POINTER(result) */
+
+
+  if(n < 0) {
+    n = -n;
+
+    if(x == 0.0) {
+      double u = 1.0 / x;
+      result->val = (n % 2) ? u : (u * u) ;  /* correct sign of infinity */
+      result->err = GSL_POSINF;
+      GSL_ERROR ("overflow", GSL_EOVRFLW);
+    }
+
+    x = 1.0/x;
+  }
+
+  /* repeated squaring method 
+   * returns 0.0^0 = 1.0, so continuous in x
+   */
+  do {
+     if(GSL_IS_ODD(n)) value *= x;
+     n >>= 1;
+     x *= x;
+     ++count;
+  } while (n);
+
+  result->val = value;
+  result->err = 2.0 * GSL_DBL_EPSILON * (count + 1.0) * fabs(value); 
+
+  return GSL_SUCCESS;
+}
+
+/*-*-*-*-*-*-*-*-*-* Functions w/ Natural Prototypes *-*-*-*-*-*-*-*-*-*-*/
+
+#include "eval.h"
+
+double gsl_sf_pow_int(const double x, const int n)
+{
+  EVAL_RESULT(gsl_sf_pow_int_e(x, n, &result));
+}