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.TH FREXP "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
.SH PROLOG
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.

.SH NAME
frexp,
frexpf,
frexpl
\(em extract mantissa and exponent from a double precision number
.SH SYNOPSIS
.LP
.nf
#include <math.h>
.P
double frexp(double \fInum\fP, int *\fIexp\fP);
float frexpf(float \fInum\fP, int *\fIexp\fP);
long double frexpl(long double \fInum\fP, int *\fIexp\fP);
.fi
.SH 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\(hy2008 defers to the ISO\ C standard.
.P
These functions shall break a floating-point number
.IR num
into a normalized fraction and an integral power of 2. The integer
exponent shall be stored in the
.BR int
object pointed to by
.IR exp .
.SH "RETURN VALUE"
For finite arguments, these functions shall return the value
.IR x ,
such that
.IR x
has a magnitude in the interval [\(12,1) or 0, and
.IR num
equals
.IR x
times 2 raised to the power *\fIexp\fP.
.P
If
.IR num
is NaN, a NaN shall be returned, and the value of *\fIexp\fP is
unspecified.
.P
If
.IR num
is \(+-0, \(+-0 shall be returned, and the value of *\fIexp\fP shall be
0.
.P
If
.IR num
is \(+-Inf,
.IR num
shall be returned, and the value of *\fIexp\fP is unspecified.
.SH ERRORS
No errors are defined.
.P
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIisnan\fR\^(\|)",
.IR "\fIldexp\fR\^(\|)",
.IR "\fImodf\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2008,
.IR "\fB<math.h>\fP"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

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