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  2016-03-15 ""  "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 .sp
  41 .BI "double modf(double " x ", double *" iptr );
  42 .br
  43 .BI "float modff(float " x ", float *" iptr );
  44 .br
  45 .BI "long double modfl(long double " x ", long double *" iptr );
  46 .fi
  47 .sp
  48 Link with \fI\-lm\fP.
  49 .sp
  50 .in -4n
  51 Feature Test Macro Requirements for glibc (see
  52 .BR feature_test_macros (7)):
  53 .in
  54 .sp
  55 .ad l
  56 .BR modf (),
  57 .BR modfl ():
  58 .RS 4
  59 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
  60     || /* Since glibc 2.19: */ _DEFAULT_SOURCE
  61     || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
  62 .RE
  63 .ad
  64 .SH DESCRIPTION
  65 These functions break the argument
  66 .I x
  67 into an integral
  68 part and a fractional part, each of which has the same sign as
  69 .IR x .
  70 The integral part is stored in the location pointed to by
  71 .IR iptr .
  72 .SH RETURN VALUE
  73 These functions return the fractional part of
  74 .IR x .
  75
  76 If
  77 .I x
  78 is a NaN, a NaN is returned, and
  79 .IR *iptr
  80 is set to a NaN.
  81
  82 If
  83 .I x
  84 is positive infinity (negative infinity), +0 (\-0) is returned, and
  85 .IR *iptr
  86 is set to positive infinity (negative infinity).
  87 .SH ERRORS
  88 No errors occur.
  89 .SH ATTRIBUTES
  90 For an explanation of the terms used in this section, see
  91 .BR attributes (7).
  92 .TS
  93 allbox;
  94 lbw24 lb lb
  95 l l l.
  96 Interface       Attribute       Value
  97 T{
  98 .BR modf (),
  99 .BR modff (),
 100 .BR modfl ()
 101 T}      Thread safety   MT-Safe
 102 .TE
 103 .SH CONFORMING TO
 104 C99, POSIX.1-2001, POSIX.1-2008.
 105
 106 The variant returning
 107 .I double
 108 also conforms to
 109 SVr4, 4.3BSD, C89.
 110 .SH SEE ALSO
 111 .BR frexp (3),
 112 .BR ldexp (3)