[unix-history] / usr / src / usr.bin / f77 / libF77 / pow_ri.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *	@(#)pow_ri.c	5.4	%G%
 */

#ifdef tahoe
#define	double	float
#endif /* tahoe */

float
pow_ri(ap, bp)
	float *ap;
	long *bp;
{
	register long n = *bp;
#ifdef tahoe
	register
#endif /* tahoe */
	double y, x = *ap;

	if (!n)
		return((double)1);
	if (n < 0) {
		x = (double)1 / x;
		n = -n;
	}
	while (!(n&1)) {
		x *= x;
		n >>= 1;
	}
	for (y = x; --n > 0; y *= x)
		while (!(n&1)) {
			x *= x;
			n >>= 1;
		}
	return(y);
}
#ifdef tahoe
#undef double
#endif /* tahoe */
Commit	Line	Data
683456d4	1	/*
a7868ad7 RE	2	* Copyright (c) 1980 Regents of the University of California.
	3	* All rights reserved. The Berkeley software License Agreement
	4	* specifies the terms and conditions for redistribution.
	5	*
d3a941af	6	* @(#)pow_ri.c 5.4 %G%
683456d4 DW	7	*/
683456d4 DW	8
d3a941af KB	9	#ifdef tahoe
	10	#define double float
	11	#endif /* tahoe */
683456d4	12
d3a941af KB	13	float
	14	pow_ri(ap, bp)
	15	float *ap;
	16	long *bp;
	17	{
	18	register long n = *bp;
	19	#ifdef tahoe
	20	register
	21	#endif /* tahoe */
	22	double y, x = *ap;
683456d4	23
d3a941af KB	24	if (!n)
	25	return((double)1);
	26	if (n < 0) {
	27	x = (double)1 / x;
683456d4	28	n = -n;
d3a941af KB	29	}
	30	while (!(n&1)) {
	31	x *= x;
	32	n >>= 1;
	33	}
	34	for (y = x; --n > 0; y *= x)
	35	while (!(n&1)) {
683456d4	36	x *= x;
d3a941af	37	n >>= 1;
683456d4	38	}
d3a941af	39	return(y);
683456d4	40	}
d3a941af KB	41	#ifdef tahoe
	42	#undef double
	43	#endif /* tahoe */