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
6 .\" preserved on all copies.
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14 .\" manual page may be incorrect or out-of-date.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
17 .\" have taken the same level of care in the production of this manual,
18 .\" which is licensed free of charge, as they might when working
21 .\" Formatted or processed versions of this manual, if unaccompanied by
22 .\" the source, must acknowledge the copyright and authors of this work.
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 MODF 3 2021-03-22 "" "Linux Programmer's Manual"
35 modf, modff, modfl \- extract signed integral and fractional values from
41 .BI "double modf(double " x ", double *" iptr );
42 .BI "float modff(float " x ", float *" iptr );
43 .BI "long double modfl(long double " x ", long double *" iptr );
49 Feature Test Macro Requirements for glibc (see
50 .BR feature_test_macros (7)):
56 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
57 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
58 || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
61 These functions break the argument
64 part and a fractional part, each of which has the same sign as
66 The integral part is stored in the location pointed to by
69 These functions return the fractional part of
74 is a NaN, a NaN is returned, and
80 is positive infinity (negative infinity), +0 (\-0) is returned, and
82 is set to positive infinity (negative infinity).
86 For an explanation of the terms used in this section, see
94 Interface Attribute Value
99 T} Thread safety MT-Safe
105 C99, POSIX.1-2001, POSIX.1-2008.
107 The variant returning