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14 .\" manual page may be incorrect or out-of-date.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
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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 2019-03-06 "" "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 );
42 .BI "float frexpf(float " x ", int *" exp );
43 .BI "long double frexpl(long double " x ", int *" exp );
49 Feature Test Macro Requirements for glibc (see
50 .BR feature_test_macros (7)):
57 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
58 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
59 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
63 These functions are used to split the number
66 normalized fraction and an exponent which is stored in
69 These functions return the normalized fraction.
73 the normalized fraction is
76 and its absolute value is always in the range 1/2 (inclusive) to
77 1 (exclusive), that is, [0.5,1).
81 is zero, then the normalized fraction is
82 zero and zero is stored in
88 a NaN is returned, and the value of
94 is positive infinity (negative infinity),
95 positive infinity (negative infinity) is returned, and the value of
101 For an explanation of the terms used in this section, see
107 Interface Attribute Value
112 T} Thread safety MT-Safe
115 C99, POSIX.1-2001, POSIX.1-2008.
117 The variant returning
122 The program below produces results such as the following:
126 .RB "$" " ./a.out 2560"
127 frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560
128 .RB "$" " ./a.out \-4"
129 frexp(\-4, &e) = \-0.5: \-0.5 * 2^3 = \-4
141 main(int argc, char *argv[])
146 x = strtod(argv[1], NULL);
149 printf("frexp(%g, &e) = %g: %g * %d^%d = %g\en",
150 x, r, r, FLT_RADIX, exp, x);