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  2015-04-19 ""  "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 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
  60 _POSIX_C_SOURCE\ >=\ 200112L;
  61 .br
  62 or
  63 .I cc\ -std=c99
  64 .RE
  65 .ad
  66 .SH DESCRIPTION
  67 These functions break the argument
  68 .I x
  69 into an integral
  70 part and a fractional part, each of which has the same sign as
  71 .IR x .
  72 The integral part is stored in the location pointed to by
  73 .IR iptr .
  74 .SH RETURN VALUE
  75 These functions return the fractional part of
  76 .IR x .
  77
  78 If
  79 .I x
  80 is a NaN, a NaN is returned, and
  81 .IR *iptr
  82 is set to a NaN.
  83
  84 If
  85 .I x
  86 is positive infinity (negative infinity), +0 (\-0) is returned, and
  87 .IR *iptr
  88 is set to positive infinity (negative infinity).
  89 .SH ERRORS
  90 No errors occur.
  91 .SH ATTRIBUTES
  92 For an explanation of the terms used in this section, see
  93 .BR attributes (7).
  94 .TS
  95 allbox;
  96 lbw24 lb lb
  97 l l l.
  98 Interface       Attribute       Value
  99 T{
 100 .BR modf (),
 101 .BR modff (),
 102 .BR modfl ()
 103 T}      Thread safety   MT-Safe
 104 .TE
 105 .SH CONFORMING TO
 106 C99, POSIX.1-2001, POSIX.1-2008.
 107
 108 The variant returning
 109 .I double
 110 also conforms to
 111 SVr4, 4.3BSD, C89.
 112 .SH SEE ALSO
 113 .BR frexp (3),
 114 .BR ldexp (3)