man3/modf.3

   1 '\" t
   2 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .\" References consulted:
   7 .\"     Linux libc source code
   8 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
   9 .\"     386BSD man pages
  10 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  11 .\" Modified 2002-07-27 by Walter Harms
  12 .\"     (walter.harms@informatik.uni-oldenburg.de)
  13 .\"
  14 .TH modf 3 (date) "Linux man-pages (unreleased)"
  15 .SH NAME
  16 modf, modff, modfl \- extract signed integral and fractional values from
  17 floating-point number
  18 .SH LIBRARY
  19 Math library
  20 .RI ( libm ", " \-lm )
  21 .SH SYNOPSIS
  22 .nf
  23 .B #include <math.h>
  24 .PP
  25 .BI "double modf(double " x ", double *" iptr );
  26 .BI "float modff(float " x ", float *" iptr );
  27 .BI "long double modfl(long double " x ", long double *" iptr );
  28 .fi
  29 .PP
  30 .RS -4
  31 Feature Test Macro Requirements for glibc (see
  32 .BR feature_test_macros (7)):
  33 .RE
  34 .PP
  35 .BR modff (),
  36 .BR modfl ():
  37 .nf
  38     _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
  39         || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  40         || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  41 .fi
  42 .SH DESCRIPTION
  43 These functions break the argument
  44 .I x
  45 into an integral
  46 part and a fractional part, each of which has the same sign as
  47 .IR x .
  48 The integral part is stored in the location pointed to by
  49 .IR iptr .
  50 .SH RETURN VALUE
  51 These functions return the fractional part of
  52 .IR x .
  53 .PP
  54 If
  55 .I x
  56 is a NaN, a NaN is returned, and
  57 .I *iptr
  58 is set to a NaN.
  59 .PP
  60 If
  61 .I x
  62 is positive infinity (negative infinity), +0 (\-0) is returned, and
  63 .I *iptr
  64 is set to positive infinity (negative infinity).
  65 .SH ERRORS
  66 No errors occur.
  67 .SH ATTRIBUTES
  68 For an explanation of the terms used in this section, see
  69 .BR attributes (7).
  70 .TS
  71 allbox;
  72 lbx lb lb
  73 l l l.
  74 Interface       Attribute       Value
  75 T{
  76 .na
  77 .nh
  78 .BR modf (),
  79 .BR modff (),
  80 .BR modfl ()
  81 T}      Thread safety   MT-Safe
  82 .TE
  83 .sp 1
  84 .SH STANDARDS
  85 C11, POSIX.1-2008.
  86 .SH HISTORY
  87 C99, POSIX.1-2001.
  88 .PP
  89 The variant returning
  90 .I double
  91 also conforms to
  92 SVr4, 4.3BSD, C89.
  93 .SH SEE ALSO
  94 .BR frexp (3),
  95 .BR ldexp (3)