man3/modf.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  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)
  32 .\"
  33 .TH MODF 3  2017-09-15 ""  "Linux Programmer's Manual"
  34 .SH NAME
  35 modf, modff, modfl \- extract signed integral and fractional values from
  36 floating-point number
  37 .SH SYNOPSIS
  38 .nf
  39 .B #include <math.h>
  40 .PP
  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 );
  44 .fi
  45 .PP
  46 Link with \fI\-lm\fP.
  47 .PP
  48 .in -4n
  49 Feature Test Macro Requirements for glibc (see
  50 .BR feature_test_macros (7)):
  51 .in
  52 .PP
  53 .ad l
  54 .BR modf (),
  55 .BR modfl ():
  56 .RS 4
  57 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  58     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  59     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  60 .RE
  61 .ad
  62 .SH DESCRIPTION
  63 These functions break the argument
  64 .I x
  65 into an integral
  66 part and a fractional part, each of which has the same sign as
  67 .IR x .
  68 The integral part is stored in the location pointed to by
  69 .IR iptr .
  70 .SH RETURN VALUE
  71 These functions return the fractional part of
  72 .IR x .
  73 .PP
  74 If
  75 .I x
  76 is a NaN, a NaN is returned, and
  77 .IR *iptr
  78 is set to a NaN.
  79 .PP
  80 If
  81 .I x
  82 is positive infinity (negative infinity), +0 (\-0) is returned, and
  83 .IR *iptr
  84 is set to positive infinity (negative infinity).
  85 .SH ERRORS
  86 No errors occur.
  87 .SH ATTRIBUTES
  88 For an explanation of the terms used in this section, see
  89 .BR attributes (7).
  90 .TS
  91 allbox;
  92 lbw24 lb lb
  93 l l l.
  94 Interface       Attribute       Value
  95 T{
  96 .BR modf (),
  97 .BR modff (),
  98 .BR modfl ()
  99 T}      Thread safety   MT-Safe
 100 .TE
 101 .SH CONFORMING TO
 102 C99, POSIX.1-2001, POSIX.1-2008.
 103 .PP
 104 The variant returning
 105 .I double
 106 also conforms to
 107 SVr4, 4.3BSD, C89.
 108 .SH SEE ALSO
 109 .BR frexp (3),
 110 .BR ldexp (3)