[unix-history] / usr / src / old / libm / libm / pow.c

/*	@(#)pow.c	4.2	%G%	*/

/*
	computes a^b.
	uses log and exp
*/

#include	<errno.h>
int errno;
double log(), exp();

double
pow(arg1,arg2)
double arg1, arg2;
{
	double temp;
	long l;

#ifdef vax
	asm("	bispsw	$0xe0");
#endif
	if(arg1 <= 0.) {
		if(arg1 == 0.) {
			if(arg2 <= 0.)
				goto domain;
			return(0.);
		}
		l = arg2;
		if(l != arg2)
			goto domain;
		temp = exp(arg2 * log(-arg1));
		if(l & 1)
			temp = -temp;
		return(temp);
	}
	return(exp(arg2 * log(arg1)));

domain:
	errno = EDOM;
	return(0.);
}
Commit	Line	Data
81bcf8af	1	/* @(#)pow.c 4.2 %G% */
a83d2d10 SL	2
	3	/*
	4	computes a^b.
	5	uses log and exp
	6	*/
	7
	8	#include <errno.h>
	9	int errno;
	10	double log(), exp();
	11
	12	double
	13	pow(arg1,arg2)
	14	double arg1, arg2;
	15	{
	16	double temp;
	17	long l;
	18
81bcf8af	19	#ifdef vax
a83d2d10	20	asm(" bispsw $0xe0");
81bcf8af	21	#endif
a83d2d10 SL	22	if(arg1 <= 0.) {
	23	if(arg1 == 0.) {
	24	if(arg2 <= 0.)
	25	goto domain;
	26	return(0.);
	27	}
	28	l = arg2;
	29	if(l != arg2)
	30	goto domain;
	31	temp = exp(arg2 * log(-arg1));
	32	if(l & 1)
	33	temp = -temp;
	34	return(temp);
	35	}
	36	return(exp(arg2 * log(arg1)));
	37
	38	domain:
	39	errno = EDOM;
	40	return(0.);
	41	}