1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
3 .\" %%%LICENSE_START(VERBATIM)
4 .\" Permission is granted to make and distribute verbatim copies of this
5 .\" manual provided the copyright notice and this permission notice are
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8 .\" Permission is granted to copy and distribute modified versions of this
9 .\" manual under the conditions for verbatim copying, provided that the
10 .\" entire resulting derived work is distributed under the terms of a
11 .\" permission notice identical to this one.
13 .\" Since the Linux kernel and libraries are constantly changing, this
14 .\" manual page may be incorrect or out-of-date. The author(s) assume no
15 .\" responsibility for errors or omissions, or for damages resulting from
16 .\" the use of the information contained herein. The author(s) may not
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18 .\" which is licensed free of charge, as they might when working
21 .\" Formatted or processed versions of this manual, if unaccompanied by
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25 .\" References consulted:
26 .\" Linux libc source code
27 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
29 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
30 .\" Modified 2002-07-27 by Walter Harms
31 .\" (walter.harms@informatik.uni-oldenburg.de)
33 .TH FREXP 3 2015-04-19 "" "Linux Programmer's Manual"
35 frexp, frexpf, frexpl \- convert floating-point number to fractional
36 and integral components
41 .BI "double frexp(double " x ", int *" exp );
43 .BI "float frexpf(float " x ", int *" exp );
45 .BI "long double frexpl(long double " x ", int *" exp );
51 Feature Test Macro Requirements for glibc (see
52 .BR feature_test_macros (7)):
59 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
60 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
61 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
68 These functions are used to split the number
71 normalized fraction and an exponent which is stored in
74 These functions return the normalized fraction.
78 the normalized fraction is
81 and its absolute value is always in the range 1/2 (inclusive) to
82 1 (exclusive), that is, [0.5,1).
86 is zero, then the normalized fraction is
87 zero and zero is stored in
93 a NaN is returned, and the value of
99 is positive infinity (negative infinity),
100 positive infinity (negative infinity) is returned, and the value of
106 For an explanation of the terms used in this section, see
112 Interface Attribute Value
117 T} Thread safety MT-Safe
120 C99, POSIX.1-2001, POSIX.1-2008.
122 The variant returning
127 The program below produces results such as the following:
131 .RB "$" " ./a.out 2560"
132 frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
133 .RB "$" " ./a.out \-4"
134 frexp(\-4, &e) = \-0.5: \-0.5 * 2^3 = \-4
146 main(int argc, char *argv[])
151 x = strtod(argv[1], NULL);
154 printf("frexp(%g, &e) = %g: %g * %d^%d = %g\\n",
155 x, r, r, FLT_RADIX, exp, x);