double frexp (      double x, int * exp );
      float frexp (       float x, int * exp );
long double frexp ( long double x, int * exp );

<cmath>

Get significand and exponent

Breaks the floating point number x into its binary significand (a floating point value between 0.5 and 1.0) and an integral exponent for 2, such that:

x = significand * 2 ^exponent

The exponent is stored in the location pointed by exp, and the significand is the value returned by the function.

If x is zero, both parts (significand and exponent) are zero.

Parameters

x

Floating point value to be computed.

exp

Pointer to an int object where the value of the exponent is to be stored.

Return Value

Portability

Example

/* frexp example */
#include <stdio.h>
#include <math.h>

int main ()
{
  double param, result;
  int n;

  param = 15.2;
  result = frexp (param , &n);
  printf ("%lf * 2^%d = %f\n", result, n, param);
  return 0;
}

Output:

0.950000 * 2^4 = 15.200000

See also