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.TH FLOOR "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
.SH 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.

.SH NAME
floor,
floorf,
floorl
\(em floor function
.SH SYNOPSIS
.LP
.nf
#include <math.h>
.P
double floor(double \fIx\fP);
float floorf(float \fIx\fP);
long double floorl(long double \fIx\fP);
.fi
.SH 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\(hy2008 defers to the ISO\ C standard.
.P
These functions shall compute the largest integral value not greater
than
.IR x .
.SH "RETURN VALUE"
The result shall have the same sign as
.IR x .
.P
Upon successful completion, these functions shall return the largest
integral value not greater than
.IR x ,
expressed as a
.BR double ,
.BR float ,
or
.BR "long double" ,
as appropriate for the return type of the function.
.P
If
.IR x
is NaN, a NaN shall be returned.
.P
If
.IR x
is \(+-0 or \(+-Inf,
.IR x
shall be returned.
.SH ERRORS
No errors are defined.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
The integral value returned by these functions might not be expressible
as an
.BR intmax_t .
The return value should be tested before assigning it to an integer
type to avoid the undefined results of an integer overflow.
.P
These functions may raise the inexact floating-point exception if the
result differs in value from the argument.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIceil\fR\^(\|)",
.IR "\fIfeclearexcept\fR\^(\|)",
.IR "\fIfetestexcept\fR\^(\|)",
.IR "\fIisnan\fR\^(\|)"
.P
.IR "Section 4.19" ", " "Treatment of Error Conditions for Mathematical Functions",
.IR "\fB<math.h>\fP"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .