.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" References consulted:
.\" Linux libc source code
.\" Modified 2002-07-27 by Walter Harms
.\" (walter.harms@informatik.uni-oldenburg.de)
.\"
-.TH FREXP 3 2002-07-27 "" "Linux Programmer's Manual"
+.TH FREXP 3 2017-09-15 "" "Linux Programmer's Manual"
.SH NAME
frexp, frexpf, frexpl \- convert floating-point number to fractional
and integral components
.SH SYNOPSIS
.nf
.B #include <math.h>
-.sp
+.PP
.BI "double frexp(double " x ", int *" exp );
-.br
.BI "float frexpf(float " x ", int *" exp );
-.br
.BI "long double frexpl(long double " x ", int *" exp );
.fi
-.sp
+.PP
Link with \fI\-lm\fP.
+.PP
+.in -4n
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.in
+.PP
+.ad l
+.BR frexpf (),
+.BR frexpl ():
+.RS 4
+_ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
+ || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+ || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.RE
+.ad
.SH DESCRIPTION
-The
-.BR frexp ()
-function is used to split the number \fIx\fP into a
-normalized fraction and an exponent which is stored in \fIexp\fP.
-.SH "RETURN VALUE"
-The
-.BR frexp ()
-function returns the normalized fraction.
-If the argument \fIx\fP is not zero,
-the normalized fraction is \fIx\fP times a power of two,
+These functions are used to split the number
+.I x
+into a
+normalized fraction and an exponent which is stored in
+.IR exp .
+.SH RETURN VALUE
+These functions return the normalized fraction.
+If the argument
+.I x
+is not zero,
+the normalized fraction is
+.I x
+times a power of two,
and its absolute value is always in the range 1/2 (inclusive) to
-1 (exclusive).
-If \fIx\fP is zero, then the normalized fraction is
-zero and zero is stored in \fIexp\fP.
-.SH "CONFORMING TO"
-SVr4, 4.3BSD, C89, C99.
-The
-.I float
-and
-.I "long double"
-variants are C99 requirements.
+1 (exclusive), that is, [0.5,1).
+.PP
+If
+.I x
+is zero, then the normalized fraction is
+zero and zero is stored in
+.IR exp .
+.PP
+If
+.I x
+is a NaN,
+a NaN is returned, and the value of
+.I *exp
+is unspecified.
+.PP
+If
+.I x
+is positive infinity (negative infinity),
+positive infinity (negative infinity) is returned, and the value of
+.I *exp
+is unspecified.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbw27 lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR frexp (),
+.BR frexpf (),
+.BR frexpl ()
+T} Thread safety MT-Safe
+.TE
+.SH CONFORMING TO
+C99, POSIX.1-2001, POSIX.1-2008.
+.PP
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
.SH EXAMPLE
-.nf
+The program below produces results such as the following:
+.PP
+.in +4n
+.EX
+.RB "$" " ./a.out 2560"
+frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
+.RB "$" " ./a.out \-4"
+frexp(\-4, &e) = \-0.5: \-0.5 * 2^3 = \-4
+.EE
+.in
+.SS Program source
+\&
+.EX
#include <math.h>
#include <float.h>
#include <stdio.h>
printf("frexp(%g, &e) = %g: %g * %d^%d = %g\\n",
x, r, r, FLT_RADIX, exp, x);
exit(EXIT_SUCCESS);
-} /* main */
-.fi
-.sp
-This program produces results such as the following:
-.sp
-.in +4n
-$ ./a.out 2560
-frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
-$ ./a.out \-4
-frexp(\-4, &e) = \-0.5: \-0.5 * 2^3 = -4
-.in
-.SH "SEE ALSO"
+}
+.EE
+.SH SEE ALSO
.BR ldexp (3),
.BR modf (3)