FREXP(3)                   POSIX Programmer's Manual                  FREXP(3)



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

NAME
       frexp, frexpf, frexpl -- extract mantissa and exponent from a double
       precision number

SYNOPSIS
       #include <math.h>

       double frexp(double num, int *exp);
       float frexpf(float num, int *exp);
       long double frexpl(long double num, int *exp);

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 a floating-point number num into a
       normalized fraction and an integral power of 2. The integer exponent
       shall be stored in the int object pointed to by exp.

RETURN VALUE
       For finite arguments, these functions shall return the value _x, such
       that _x has a magnitude in the interval [1/2,1) or 0, and num equals _x
       times 2 raised to the power *exp.

       If num is NaN, a NaN shall be returned, and the value of *exp is
       unspecified.

       If num is +-0, +-0 shall be returned, and the value of *exp shall be 0.

       If num is +-Inf, num shall be returned, and the value of *exp is
       unspecified.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       isnan(), ldexp(), modf()

       The Base Definitions volume of POSIX.1-2017, <math.h>

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                             FREXP(3)
