phoenix-rtos-doc / libc / functions / f / frexp.part-impl.md

frexp

Synopsis

#include <math.h>

double frexp(double num, int *exp);

float frexpf(float num, int *exp);

Status

Partially implemented

Conformance

IEEE Std 1003.1-2017

Description

The purpose is to extract mantissa and exponent from a double precision number. 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.

Tests

Untested

Known bugs

None