frexp

Gets the mantissa and exponent of a floating-point number.

doublefrexp(doublex**,int*expptr);**

For additional compatibility information, see Compatibility in the Introduction.

Libraries

Return Value

frexp returns the mantissa. If x is 0, the function returns 0 for both the mantissa and the exponent. There is no error return.

Parameters

x

Floating-point value

expptr

Pointer to stored integer exponent

Remarks

The frexp function breaks down the floating-point value (x) into a mantissa (m) and an exponent (n), such that the absolute value of m is greater than or equal to 0.5 and less than 1.0, and x = m*2ⁿ. The integer exponent n is stored at the location pointed to by expptr.

Example

/* FREXP.C: This program calculates frexp( 16.4, &n )
 * then displays y and n.
 */

#include <math.h>
#include <stdio.h>

void main( void )
{
   double x, y;
   int n;

   x = 16.4;
   y = frexp( x, &n );
   printf( "frexp( %f, &n ) = %f, n = %d\n", x, y, n );
}

Output

frexp( 16.400000, &n ) = 0.512500, n = 5

Floating-Point Support Routines

See Also   ldexp, modf