modf(3p) — Linux manual page

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

PROLOG

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

NAME

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

SYNOPSIS

       #include <math.h>

       double modf(double x, double *iptr);
       float modff(float value, float *iptr);
       long double modfl(long double value, long double *iptr);

DESCRIPTION

       The functionality described on this reference page is aligned
       with the ISO C standard. Any conflict between the requirements
       described here and the ISO C standard is unintentional. This
       volume of POSIX.1‐2017 defers to the ISO C standard.

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

RETURN VALUE

       Upon successful completion, these functions shall return the
       signed fractional part of x.

       If x is NaN, a NaN shall be returned, and *iptr shall be set to a
       NaN.

       If x is ±Inf, ±0 shall be returned, and *iptr shall be set to
       ±Inf.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The modf() function computes the function result and *iptr such
       that:

           a = modf(x, iptr) ;
           x == a+*iptr ;

       allowing for the usual floating-point inaccuracies.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       frexp(3p), isnan(3p), ldexp(3p)

       The Base Definitions volume of POSIX.1‐2017, math.h(0p)

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                          MODF(3P)

Pages that refer to this page: math.h(0p), tgmath.h(0p), frexp(3p)

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