1 files changed, 54 insertions, 0 deletions
diff --git a/gsl-1.9/sys/pow_int.c b/gsl-1.9/sys/pow_int.c
new file mode 100644
index 0000000..cd29d2f
--- /dev/null
+++ b/gsl-1.9/sys/pow_int.c
@@ -0,0 +1,54 @@
+/* sys/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.
+ */
+#include <config.h>
+#include <math.h>
+#include <gsl/gsl_pow_int.h>
+
+#ifndef HIDE_INLINE_STATIC
+double gsl_pow_2(const double x) { return x*x;   }
+double gsl_pow_3(const double x) { return x*x*x; }
+double gsl_pow_4(const double x) { double x2 = x*x;   return x2*x2;    }
+double gsl_pow_5(const double x) { double x2 = x*x;   return x2*x2*x;  }
+double gsl_pow_6(const double x) { double x2 = x*x;   return x2*x2*x2; }
+double gsl_pow_7(const double x) { double x3 = x*x*x; return x3*x3*x;  }
+double gsl_pow_8(const double x) { double x2 = x*x;   double x4 = x2*x2; return x4*x4; }
+double gsl_pow_9(const double x) { double x3 = x*x*x; return x3*x3*x3; }
+#endif
+
+double gsl_pow_int(double x, int n)
+{
+  double value = 1.0;
+
+  if(n < 0) {
+    x = 1.0/x;
+    n = -n;
+  }
+
+  /* repeated squaring method 
+   * returns 0.0^0 = 1.0, so continuous in x
+   */
+  do {
+     if(n & 1) value *= x;  /* for n odd */
+     n >>= 1;
+     x *= x;
+  } while (n);
+
+  return value;
+}
+