PROLOG

       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

       floor, floorf, floorl — floor function

SYNOPSIS

       #include <math.h>

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

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 compute the largest integral value not greater than x.

RETURN VALUE

       The result shall have the same sign as x.

       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.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

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

       These  functions  may  raise the inexact floating-point exception if the result differs in
       value from the argument.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       ceil(), feclearexcept(), fetestexcept(), isnan()

       Section 4.20, Treatment of Error Conditions for Mathematical Functions, <math.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1-2017,  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 .