man3/floor.3

   1 .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
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  23 .TH FLOOR 3  2001-05-31 "" "Linux Programmer's Manual"
  24 .SH NAME
  25 floor, floorf, floorl \- largest integral value not greater than argument
  26 .SH SYNOPSIS
  27 .nf
  28 .B #include <math.h>
  29 .sp
  30 .BI "double floor(double " x );
  31 .br
  32 .BI "float floorf(float " x );
  33 .br
  34 .BI "long double floorl(long double " x );
  35 .fi
  36 .sp
  37 Link with \fI-lm\fP.
  38 .SH DESCRIPTION
  39 These functions round \fIx\fP down to the nearest integer.
  40 .SH "RETURN VALUE"
  41 The rounded integer value.
  42 If \fIx\fP is integral or infinite,
  43 \fIx\fP itself is returned.
  44 .SH ERRORS
  45 No errors other than
  46 .B EDOM
  47 and
  48 .B ERANGE
  49 can occur.
  50 If \fIx\fP is NaN, then NaN is returned and
  51 .I errno
  52 may be set to
  53 .BR EDOM .
  54 .SH "CONFORMING TO"
  55 The
  56 .BR floor ()
  57 function conforms to SVr4, 4.3BSD, C89.
  58 The other functions are from C99.
  59 .SH NOTES
  60 SUSv2 and POSIX.1-2001 contain text about overflow (which might set
  61 .I errno
  62 to
  63 .BR ERANGE ,
  64 or raise an exception).
  65 In practice, the result cannot overflow on any current machine,
  66 so this error-handling stuff is just nonsense.
  67 (More precisely, overflow can happen only when the maximum value
  68 of the exponent is smaller than the number of mantissa bits.
  69 For the IEEE-754 standard 32-bit and 64-bit floating point numbers
  70 the maximum value of the exponent is 128 (resp. 1024), and the number
  71 of mantissa bits is 24 (resp. 53).)
  72 .SH "SEE ALSO"
  73 .BR ceil (3),
  74 .BR lrint (3),
  75 .BR nearbyint (3),
  76 .BR rint (3),
  77 .BR round (3),
  78 .BR trunc (3)