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

12       modf, modff, modfl - decompose a floating-point number
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SYNOPSIS

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

23       These functions shall break the argument x into integral and fractional
24       parts,  each  of which has the same sign as the argument. It stores the
25       integral part as a double (for the modf() function), a float  (for  the
26       modff()  function), or a long double (for the modfl() function), in the
27       object pointed to by iptr.
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RETURN VALUE

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

38       No errors are defined.
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40       The following sections are informative.
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EXAMPLES

43       None.
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APPLICATION USAGE

46       The modf() function computes the function result and *iptr such that:
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49              a = modf(x, iptr) ;
50              x == a+*iptr ;
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52       allowing for the usual floating-point inaccuracies.
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RATIONALE

55       None.
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FUTURE DIRECTIONS

58       None.
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SEE ALSO

61       frexp(),   isnan(),   ldexp(),   the   Base   Definitions   volume   of
62       IEEE Std 1003.1-2001, <math.h>
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65       Portions of this text are reprinted and reproduced in  electronic  form
66       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
67       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
68       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
69       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
70       event of any discrepancy between this version and the original IEEE and
71       The Open Group Standard, the original IEEE and The Open Group  Standard
72       is  the  referee document. The original Standard can be obtained online
73       at http://www.opengroup.org/unix/online.html .
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77IEEE/The Open Group                  2003                             MODF(3P)
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