1MODF(3P)                   POSIX Programmer's Manual                  MODF(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

13       modf, modff, modfl — decompose a floating-point number
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SYNOPSIS

16       #include <math.h>
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18       double modf(double x, double *iptr);
19       float modff(float value, float *iptr);
20       long double modfl(long double value, long double *iptr);
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DESCRIPTION

23       The functionality described on this reference page is aligned with  the
24       ISO C  standard.  Any  conflict between the requirements described here
25       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
26       defers to the ISO C standard.
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28       These functions shall break the argument x into integral and fractional
29       parts, each of which has the same sign as the argument. It  stores  the
30       integral  part  as a double (for the modf() function), a float (for the
31       modff() function), or a long double (for the modfl() function), in  the
32       object pointed to by iptr.
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RETURN VALUE

35       Upon  successful  completion,  these  functions shall return the signed
36       fractional part of x.
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38       If x is NaN, a NaN shall be returned, and *iptr shall be set to a NaN.
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40       If x is ±Inf, ±0 shall be returned, and *iptr shall be set to ±Inf.
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ERRORS

43       No errors are defined.
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45       The following sections are informative.
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EXAMPLES

48       None.
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APPLICATION USAGE

51       The modf() function computes the function result and *iptr such that:
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53           a = modf(x, iptr) ;
54           x == a+*iptr ;
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56       allowing for the usual floating-point inaccuracies.
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RATIONALE

59       None.
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FUTURE DIRECTIONS

62       None.
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SEE ALSO

65       frexp(), isnan(), ldexp()
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67       The Base Definitions volume of POSIX.1‐2008, <math.h>
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70       Portions of this text are reprinted and reproduced in  electronic  form
71       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
72       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
73       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
74       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
75       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
76       event of any discrepancy between this version and the original IEEE and
77       The  Open Group Standard, the original IEEE and The Open Group Standard
78       is the referee document. The original Standard can be  obtained  online
79       at http://www.unix.org/online.html .
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81       Any  typographical  or  formatting  errors that appear in this page are
82       most likely to have been introduced during the conversion of the source
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88IEEE/The Open Group                  2013                             MODF(3P)
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