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diff --git a/libgfortran/m4/pow.m4 b/libgfortran/m4/pow.m4
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+++ b/libgfortran/m4/pow.m4
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+`/* Support routines for the intrinsic power (**) operator.
+   Copyright 2004 Free Software Foundation, Inc.
+   Contributed by Paul Brook
+
+This file is part of the GNU Fortran 95 runtime library (libgfor).
+
+Libgfor is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public
+License as published by the Free Software Foundation; either
+version 2.1 of the License, or (at your option) any later version.
+
+Ligbfor 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with libgfor; see the file COPYING.LIB.  If not,
+write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+#include "config.h"
+#include "libgfortran.h"'
+include(iparm.m4)dnl
+
+/* Uuse Binary Method to calculate the powi. This is not an optimal but
+   a simple and reasonable arithmetic. See section 4.6.3, "Evaluation of
+   Powers" of Donald E. Knuth, "Seminumerical Algorithms", Vol. 2, "The Art
+   of Computer Programming", 3rd Edition, 1998.  */
+
+rtype_name
+`prefix(pow_'rtype_code`_'atype_code) (rtype_name a, atype_name b)
+{
+  rtype_name pow, x;
+  atype_name n, u;
+  
+  n = b;
+  x = a;
+  pow = 1;
+  if (n != 0)
+    {
+      if (n < 0)
+	{
+ifelse(rtype_letter,i,`dnl
+	  if (x == 1)
+	    return 1;
+	  if (x == -1)
+	    return (n & 1) ? -1 : 1;
+	  return (x == 0) ? 1 / x : 0;
+',`
+	  n = -n;
+	  x = pow / x;
+')dnl
+	}
+      u = n;
+      for (;;)
+	{
+	  if (u & 1)
+	    pow *= x;
+	  u >>= 1;
+	  if (u)
+	    x *= x;
+	  else
+	    break;
+	}
+    }
+  return pow;
+}