### frexp -- Separate Floating-Point Value

Format

>     #include <math.h>
>     double frexp(double x, int *expptr);

Language Level: ANSI, POSIX, XPG4
frexp breaks down the floating-point value x into a term m for the mantissa and another term n for the exponent, such that x = m * (2**n), and the absolute value of m is greater than or equal to 0.5 and less than 1.0 or equal to 0. frexp stores the integer exponent n at the location to which expptr points.

Return Value
frexp returns the mantissa term m. If x is 0, frexp returns 0 for both the mantissa and exponent. The mantissa has the same sign as the argument x. The result of the frexp function cannot have a range error.

Example
This example decomposes the floating-point value of x, 16.4, into its mantissa 0.5125, and its exponent 5. It stores the mantissa in y and the exponent in n.

    #include <math.h>
    #include <stdio.h>
    int main(void)
    {
       double x, m;
       int n;
       x = 16.4;
       m = frexp(x, &n);
       printf("The mantissa is %lf and the exponent is %d\n", m, n);
       return 0;

       /*************************************************************
          The output should be:

          The mantissa is 0.512500 and the exponent is 5
       *************************************************************/
    }

ldexp -- Multiply by a Power of Two
modf -- Separate Floating-Point Value
<math.h>