frexp(3p) — Linux manual page

```FREXP(3P)               POSIX Programmer's Manual              FREXP(3P)
```

PROLOG         top

```       This manual page is part of the POSIX Programmer's Manual.  The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
```

NAME         top

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

SYNOPSIS         top

```       #include <math.h>

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

DESCRIPTION         top

```       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         top

```       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         top

```       No errors are defined.

The following sections are informative.
```

EXAMPLES         top

```       None.
```

APPLICATION USAGE         top

```       None.
```

RATIONALE         top

```       None.
```

FUTURE DIRECTIONS         top

```       None.
```

```       isnan(3p), ldexp(3p), modf(3p)

The Base Definitions volume of POSIX.1‐2017, math.h(0p)
```

```       Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group.  In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .