contrib/libf2c/libF77/pow_di.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32

#include "f2c.h"

double
pow_di (doublereal * ap, integer * bp)
{
  double pow, x;
  integer n;
  unsigned long u;

  pow = 1;
  x = *ap;
  n = *bp;

  if (n != 0)
    {
      if (n < 0)
	{
	  n = -n;
	  x = 1 / x;
	}
      for (u = n;;)
	{
	  if (u & 01)
	    pow *= x;
	  if (u >>= 1)
	    x *= x;
	  else
	    break;
	}
    }
  return (pow);
}