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

/* @(#)frexp.c	4.2 (Berkeley) %G% */
/*
	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
be56fc55	1	/* @(#)frexp.c 4.2 (Berkeley) %G% */
29aaea38 BJ	2	/*
	3	the call
	4	x = frexp(arg,&exp);
	5	must return a double fp quantity x which is <1.0
	6	and the corresponding binary exponent "exp".
	7	such that
	8	arg = x*2^exp
be56fc55	9	if the argument is 0.0, return 0.0 mantissa and 0 exponent.
29aaea38 BJ	10	*/
	11
	12	double
	13	frexp(x,i)
	14	double x;
	15	int *i;
	16	{
	17	int neg;
	18	int j;
	19	j = 0;
	20	neg = 0;
	21	if(x<0){
	22	x = -x;
	23	neg = 1;
	24	}
be56fc55 RC	25	if(x>=1.0)
be56fc55 RC	26	while(x>=1.0){
29aaea38 BJ	27	j = j+1;
	28	x = x/2;
	29	}
be56fc55	30	else if(x<0.5 && x != 0.0)
29aaea38 BJ	31	while(x<0.5){
	32	j = j-1;
	33	x = 2*x;
	34	}
	35	*i = j;
	36	if(neg) x = -x;
	37	return(x);
	38	}