trusty (3) floorf.3posix.gz

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NAME
       floor, floorf, floorl - floor function


SYNOPSIS
       #include <math.h>

       double floor(double x);
       float floorf(float x);
       long double floorl(long double x);


DESCRIPTION
       These functions shall compute the largest integral value not greater than x.

       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 largest integral value not greater than x,
       expressed as a double, float, or long double, as appropriate for the return type of the function.

       If x is NaN, a NaN shall be returned.

       If x is ±0 or ±Inf, x shall be returned.

       If the correct value would cause overflow, a range error shall occur and floor(), floorf(), and  floorl()
       shall return the value of the macro -HUGE_VAL, -HUGE_VALF, and -HUGE_VALL, respectively.


ERRORS
       These functions shall fail if:

       Range Error
              The result would cause an overflow.

       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 following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       The  integral  value  returned  by these functions might not be expressible as an int or long. The return
       value should be tested before assigning it to an integer type  to  avoid  the  undefined  results  of  an
       integer overflow.

       The  floor()  function  can  only  overflow  when  the  floating-point  representation has DBL_MANT_DIG >
       DBL_MAX_EXP.

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


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- 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 .