MODF(3)                   (2017-09-15)                    MODF(3)

     NAME
          modf, modff, modfl - extract signed integral and fractional
          values from floating-point number

     SYNOPSIS
          #include <math.h>

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

          Link with -lm.

     Feature Test Macro Requirements for glibc (see
     feature_test_macros(7)):

          modff(), modfl():
              _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
                  || /* Since glibc 2.19: */ _DEFAULT_SOURCE
                  || /* Glibc versions <= 2.19: */ _BSD_SOURCE ||
              _SVID_SOURCE

     DESCRIPTION
          These functions break the argument x into an  integral  part
          and a fractional part, each of which has the same sign as x.
          The integral part is stored in the location  pointed  to  by
          iptr.

     RETURN VALUE
          These functions return the fractional part of x.

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

          If x is positive infinity (negative infinity),  +0  (-0)  is
          returned,  and  *iptr  is set to positive infinity (negative
          infinity).

     ERRORS
          No errors occur.

     ATTRIBUTES
          For an explanation of the terms used in  this  section,  see
          attributes(7).     allbox;    lbw24    lb    lb   l   l   l.
          Interface Attribute Value  T{   modf(),   modff(),   modfl()
          T}   Thread safety  MT-Safe

     CONFORMING TO
          C99, POSIX.1-2001, POSIX.1-2008.

          The variant returning double also conforms to SVr4,  4.3BSD,

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     MODF(3)                   (2017-09-15)                    MODF(3)

          C89.

     SEE ALSO
          frexp(3), ldexp(3)

     COLOPHON
          This page is part of release 5.10  of  the  Linux  man-pages
          project.   A  description  of the project, information about
          reporting bugs, and the latest version of this page, can  be
          found at https://www.kernel.org/doc/man-pages/.

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