NAME

frexp, frexpf, frexpl - extract mantissa and exponent from a double precision number

SYNOPSIS

#include <math.h>

double frexp(double num, int *exp);
float frexpf(float num, int *exp);
long double frexpl(long double num, int *exp);


DESCRIPTION

^[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.

These functions shall break a floating-point number num into a normalized fraction and an integral power of 2. The integer exponent shall be stored in the int object pointed to by exp.

RETURN VALUE

For finite arguments, these functions shall return the value x, such that x has a magnitude in the interval [½,1) or 0, and num equals x times 2 raised to the power *exp.

^[MX] If num is NaN, a NaN shall be returned, and the value of *exp is unspecified.

If num is ±0, ±0 shall be returned, and the value of *exp shall be 0.

If num is ±Inf, num shall be returned, and the value of *exp is unspecified.

ERRORS

No errors are defined.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

isnan, ldexp, modf

XBD <math.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 5

The DESCRIPTION is updated to indicate how an application should check for an error. This text was previously published in the APPLICATION USAGE section.

Issue 6

The frexpf() and frexpl() functions are added for alignment with the ISO/IEC 9899:1999 standard.

The DESCRIPTION, RETURN VALUE, ERRORS, and APPLICATION USAGE sections are revised to align with the ISO/IEC 9899:1999 standard.

IEC 60559:1989 standard floating-point extensions over the ISO/IEC 9899:1999 standard are marked.