4.3BSD beta release manual page

[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);
       }