[unix-history] / usr / src / lib / libc / gen / frexp.c

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)frexp.c	5.2 (Berkeley) %G%";
#endif LIBC_SCCS and not lint

/*
 *	the call
 *		x = frexp(arg,&exp);
 *	must return a double fp quantity x which is <1.0
 *	and the corresponding binary exponent "exp".
 *	such that
 *		arg = x*2^exp
 *	if the argument is 0.0, return 0.0 mantissa and 0 exponent.
 */

double
frexp(x,i)
double x;
int *i;
{
	int neg;
	int j;
	j = 0;
	neg = 0;
	if(x<0){
		x = -x;
		neg = 1;
		}
	if(x>=1.0)
		while(x>=1.0){
			j = j+1;
			x = x/2;
			}
	else if(x<0.5 && x != 0.0)
		while(x<0.5){
			j = j-1;
			x = 2*x;
			}
	*i = j;
	if(neg) x = -x;
	return(x);
	}
Commit	Line	Data
2ce81398 DS	1	#if defined(LIBC_SCCS) && !defined(lint)
	2	static char sccsid[] = "@(#)frexp.c 5.2 (Berkeley) %G%";
	3	#endif LIBC_SCCS and not lint
b8f253e8	4
29aaea38	5	/*
b8f253e8 KM	6	* the call
	7	* x = frexp(arg,&exp);
	8	* must return a double fp quantity x which is <1.0
	9	* and the corresponding binary exponent "exp".
	10	* such that
	11	* arg = x*2^exp
	12	* if the argument is 0.0, return 0.0 mantissa and 0 exponent.
	13	*/
29aaea38 BJ	14
	15	double
	16	frexp(x,i)
	17	double x;
	18	int *i;
	19	{
	20	int neg;
	21	int j;
	22	j = 0;
	23	neg = 0;
	24	if(x<0){
	25	x = -x;
	26	neg = 1;
	27	}
be56fc55 RC	28	if(x>=1.0)
be56fc55 RC	29	while(x>=1.0){
29aaea38 BJ	30	j = j+1;
	31	x = x/2;
	32	}
be56fc55	33	else if(x<0.5 && x != 0.0)
29aaea38 BJ	34	while(x<0.5){
	35	j = j-1;
	36	x = 2*x;
	37	}
	38	*i = j;
	39	if(neg) x = -x;
	40	return(x);
	41	}