fdim(3p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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

PROLOG         top

       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         top

       fdim, fdimf, fdiml — compute positive difference between two
       floating-point numbers

SYNOPSIS         top

       #include <math.h>

       double fdim(double x, double y);
       float fdimf(float x, float y);
       long double fdiml(long double x, long double y);

DESCRIPTION         top

       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 determine the positive difference between
       their arguments. If x is greater than y, x-y is returned. If x is
       less than or equal to y, +0 is returned.

       An application wishing to check for error situations should set
       errno to zero and call feclearexcept(FE_ALL_EXCEPT) before
       calling these functions. On return, if errno is non-zero or
       fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
       FE_UNDERFLOW) is non-zero, an error has occurred.

RETURN VALUE         top

       Upon successful completion, these functions shall return the
       positive difference value.

       If x-y is positive and overflows, a range error shall occur and
       fdim(), fdimf(), and fdiml() shall return the value of the macro
       HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.

       If the correct value would cause underflow, a range error may
       occur, and fdim(), fdimf(), and fdiml() shall return the correct
       value, or (if the IEC 60559 Floating-Point option is not
       supported) an implementation-defined value no greater in
       magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.

       If x or y is NaN, a NaN shall be returned.

ERRORS         top

       The fdim() function shall fail if:

       Range Error The result overflows.

                   If the integer expression (math_errhandling &
                   MATH_ERRNO) is non-zero, then errno shall be set to
                   [ERANGE].  If the integer expression
                   (math_errhandling & MATH_ERREXCEPT) is non-zero, then
                   the overflow floating-point exception shall be
                   raised.

       The fdim() function may fail if:

       Range Error The result underflows.

                   If the integer expression (math_errhandling &
                   MATH_ERRNO) is non-zero, then errno shall be set to
                   [ERANGE].  If the integer expression
                   (math_errhandling & MATH_ERREXCEPT) is non-zero, then
                   the underflow floating-point exception shall be
                   raised.

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       On error, the expressions (math_errhandling & MATH_ERRNO) and
       (math_errhandling & MATH_ERREXCEPT) are independent of each
       other, but at least one of them must be non-zero.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       feclearexcept(3p), fetestexcept(3p), fmax(3p), fmin(3p)

       Section 4.20, Treatment of Error Conditions for Mathematical
       Functions, math.h(0p)

COPYRIGHT         top

       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                          FDIM(3P)

Pages that refer to this page: math.h(0p)fmax(3p)fmin(3p)