frexp

FREXP(3)                   Linux Programmer's Manual                  FREXP(3)



NAME
       frexp, frexpf, frexpl - convert floating-point number to fractional and
       integral components

SYNOPSIS
       #include <math.h>

       double frexp(double x, int *exp);

       float frexpf(float x, int *exp);

       long double frexpl(long double x, int *exp);

DESCRIPTION
       The frexp() function is used to split the number x  into  a  normalized
       fraction and an exponent which is stored in exp.

RETURN VALUE
       The  frexp() function returns the normalized fraction.  If the argument
       x is not zero, the normalized fraction is x times a power of  two,  and
       is always in the range 1/2 (inclusive) to 1 (exclusive).  If x is zero,
       then the normalized fraction is zero and zero is stored in exp.

CONFORMING TO
       SVID 3, POSIX, BSD 4.3, ISO 9899.  The float and the long double  vari-
       ants are C99 requirements.

EXAMPLE
       #include <stdio.h>
       #include <math.h>
       #include <float.h>
       int main () {
               double d = 2560;
               int e;
               double f = frexp(d, &e);
               printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n",
                      d, f, f, FLT_RADIX, e, d);
               return 0;
       }

       This program prints

            frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560

SEE ALSO
       ldexp(3), modf(3)



                                  2002-07-27                          FREXP(3)