220 lines
5.0 KiB
HTML
220 lines
5.0 KiB
HTML
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
<HTML><HEAD><TITLE>Man page of FREXP</TITLE>
|
|
</HEAD><BODY>
|
|
<H1>FREXP</H1>
|
|
Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
|
|
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
|
|
|
|
<A NAME="lbAB"> </A>
|
|
<H2>NAME</H2>
|
|
|
|
frexp, frexpf, frexpl - convert floating-point number to fractional
|
|
and integral components
|
|
<A NAME="lbAC"> </A>
|
|
<H2>SYNOPSIS</H2>
|
|
|
|
<PRE>
|
|
<B>#include <<A HREF="file:///usr/include/math.h">math.h</A>></B>
|
|
|
|
<B>double frexp(double </B><I>x</I><B>, int *</B><I>exp</I><B>);</B>
|
|
<B>float frexpf(float </B><I>x</I><B>, int *</B><I>exp</I><B>);</B>
|
|
<B>long double frexpl(long double </B><I>x</I><B>, int *</B><I>exp</I><B>);</B>
|
|
</PRE>
|
|
|
|
<P>
|
|
|
|
Link with <I>-lm</I>.
|
|
<P>
|
|
|
|
|
|
Feature Test Macro Requirements for glibc (see
|
|
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
|
|
|
|
|
|
<P>
|
|
|
|
|
|
<B>frexpf</B>(),
|
|
|
|
<B>frexpl</B>():
|
|
|
|
<DL COMPACT><DT id="1"><DD>
|
|
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|
|
<BR> || /* Since glibc 2.19: */ _DEFAULT_SOURCE
|
|
<BR> || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
|
|
</DL>
|
|
|
|
|
|
<A NAME="lbAD"> </A>
|
|
<H2>DESCRIPTION</H2>
|
|
|
|
These functions are used to split the number
|
|
<I>x</I>
|
|
|
|
into a
|
|
normalized fraction and an exponent which is stored in
|
|
<I>exp</I>.
|
|
|
|
<A NAME="lbAE"> </A>
|
|
<H2>RETURN VALUE</H2>
|
|
|
|
These functions return the normalized fraction.
|
|
If the argument
|
|
<I>x</I>
|
|
|
|
is not zero,
|
|
the normalized fraction is
|
|
<I>x</I>
|
|
|
|
times a power of two,
|
|
and its absolute value is always in the range 1/2 (inclusive) to
|
|
1 (exclusive), that is, [0.5,1).
|
|
<P>
|
|
|
|
If
|
|
<I>x</I>
|
|
|
|
is zero, then the normalized fraction is
|
|
zero and zero is stored in
|
|
<I>exp</I>.
|
|
|
|
<P>
|
|
|
|
If
|
|
<I>x</I>
|
|
|
|
is a NaN,
|
|
a NaN is returned, and the value of
|
|
<I>*exp</I>
|
|
|
|
is unspecified.
|
|
<P>
|
|
|
|
If
|
|
<I>x</I>
|
|
|
|
is positive infinity (negative infinity),
|
|
positive infinity (negative infinity) is returned, and the value of
|
|
<I>*exp</I>
|
|
|
|
is unspecified.
|
|
<A NAME="lbAF"> </A>
|
|
<H2>ERRORS</H2>
|
|
|
|
No errors occur.
|
|
<A NAME="lbAG"> </A>
|
|
<H2>ATTRIBUTES</H2>
|
|
|
|
For an explanation of the terms used in this section, see
|
|
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
|
|
|
|
<TABLE BORDER>
|
|
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
|
|
<TR VALIGN=top><TD>
|
|
<B>frexp</B>(),
|
|
|
|
<B>frexpf</B>(),
|
|
|
|
<B>frexpl</B>()
|
|
|
|
</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
|
|
</TABLE>
|
|
|
|
<A NAME="lbAH"> </A>
|
|
<H2>CONFORMING TO</H2>
|
|
|
|
C99, POSIX.1-2001, POSIX.1-2008.
|
|
<P>
|
|
|
|
The variant returning
|
|
<I>double</I>
|
|
|
|
also conforms to
|
|
SVr4, 4.3BSD, C89.
|
|
<A NAME="lbAI"> </A>
|
|
<H2>EXAMPLE</H2>
|
|
|
|
The program below produces results such as the following:
|
|
<P>
|
|
|
|
|
|
|
|
$<B> ./a.out 2560</B>
|
|
|
|
frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
|
|
$<B> ./a.out -4</B>
|
|
|
|
frexp(-4, &e) = -0.5: -0.5 * 2^3 = -4
|
|
|
|
|
|
<A NAME="lbAJ"> </A>
|
|
<H3>Program source</H3>
|
|
|
|
|
|
|
|
#include <<A HREF="file:///usr/include/math.h">math.h</A>>
|
|
#include <<A HREF="file:///usr/include/float.h">float.h</A>>
|
|
#include <<A HREF="file:///usr/include/stdio.h">stdio.h</A>>
|
|
#include <<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>>
|
|
<P>
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
<BR> double x, r;
|
|
<BR> int exp;
|
|
<P>
|
|
<BR> x = strtod(argv[1], NULL);
|
|
<BR> r = frexp(x, &exp);
|
|
<P>
|
|
<BR> printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n",
|
|
<BR> x, r, r, FLT_RADIX, exp, x);
|
|
<BR> exit(EXIT_SUCCESS);
|
|
}
|
|
|
|
<A NAME="lbAK"> </A>
|
|
<H2>SEE ALSO</H2>
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+ldexp">ldexp</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+modf">modf</A></B>(3)
|
|
|
|
<A NAME="lbAL"> </A>
|
|
<H2>COLOPHON</H2>
|
|
|
|
This page is part of release 5.05 of the Linux
|
|
<I>man-pages</I>
|
|
|
|
project.
|
|
A description of the project,
|
|
information about reporting bugs,
|
|
and the latest version of this page,
|
|
can be found at
|
|
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
|
|
<P>
|
|
|
|
<HR>
|
|
<A NAME="index"> </A><H2>Index</H2>
|
|
<DL>
|
|
<DT id="2"><A HREF="#lbAB">NAME</A><DD>
|
|
<DT id="3"><A HREF="#lbAC">SYNOPSIS</A><DD>
|
|
<DT id="4"><A HREF="#lbAD">DESCRIPTION</A><DD>
|
|
<DT id="5"><A HREF="#lbAE">RETURN VALUE</A><DD>
|
|
<DT id="6"><A HREF="#lbAF">ERRORS</A><DD>
|
|
<DT id="7"><A HREF="#lbAG">ATTRIBUTES</A><DD>
|
|
<DT id="8"><A HREF="#lbAH">CONFORMING TO</A><DD>
|
|
<DT id="9"><A HREF="#lbAI">EXAMPLE</A><DD>
|
|
<DL>
|
|
<DT id="10"><A HREF="#lbAJ">Program source</A><DD>
|
|
</DL>
|
|
<DT id="11"><A HREF="#lbAK">SEE ALSO</A><DD>
|
|
<DT id="12"><A HREF="#lbAL">COLOPHON</A><DD>
|
|
</DL>
|
|
<HR>
|
|
This document was created by
|
|
<A HREF="/cgi-bin/man/man2html">man2html</A>,
|
|
using the manual pages.<BR>
|
|
Time: 00:05:43 GMT, March 31, 2021
|
|
</BODY>
|
|
</HTML>
|