frexp man page

Prolog

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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

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.1‐2008 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.

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.

The following sections are informative.

See Also

isnan(), ldexp(), modf()

The Base Definitions volume of POSIX.1‐2008, <math.h>

Info

2013 IEEE/The Open Group POSIX Programmer's Manual