posix man page for fdimf

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

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

SYNOPSIS
       #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
       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
       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  x-  y is positive and underflows, a range error may occur, and either ( x- y) (if representable),  or 0.0 (if supported),  or an imple-
       mentation-defined value shall be returned.

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

ERRORS
       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
       None.

APPLICATION USAGE
       On implementations supporting IEEE Std 754-1985, x- y cannot underflow, and hence the 0.0 return value is shaded as an extension for imple-
       mentations supporting the XSI extension rather than an MX extension.

       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
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       feclearexcept() , fetestexcept() , fmax() , fmin() , the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of  Error
       Conditions for Mathematical Functions, <math.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .

IEEE
/The Open Group						       2003								   FDIM(P)