FLOOR(3M) FLOOR(3M)
floor, floorl, ffloor, floorf, ceil, ceill, fceil, ceilf, copysign,
copysignl, drem, dreml, fmod, fmodl, fmodf, fabsl, fabs, fabsf,
remainder, rint, rintl, trunc, truncl, ftrunc, truncf - floor, ceiling,
remainder, absolute value, nearest integer, and truncation functions
#include <math.h>
double floor (double x);
long double floorl (long double x);
float ffloor (float x);
float floorf (float x);
double ceil (double x);
long double ceill (long double x);
float fceil (float x);
float ceilf (float x);
double copysign (double x, double y);
long double copysignl \
(long double x, long double y);
double drem (double x, double y);
long double dreml \
(long double x, long double y);
double remainder (double x, double y);
double trunc (double x);
long double truncl (long double x);
float ftrunc (float x);
float truncf (float x);
double fmod (double x, double y);
long double fmodl \
(long double x, long double y);
float fmodf (float x, float y);
double fabs (double x);
long double fabsl (long double x);
float fabsf (float x);
double rint (double x);
long double rintl (long double x);
The fmod, fabs, and trunc functions listed above, as well as the long
double and single-precision versions of the remaining functions, are only
available in the standard math library, -lm, and in -lmx.
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FLOOR(3M) FLOOR(3M)
The floor functions return the largest integer not greater than x. The
argument x is double for floor, long double for floorl, and float for
ffloor and its ANSI-named equivalent floorf.
copysign(x,y) returns the number with the magnitude of x and the sign of
y. copysignl is the long double counterpart of copysign.
drem(x,y) returns the remainder r := x - n*y where n is the integer
nearest the exact value of x/y; moreover if |n-x/y|=1/2 then n is even.
Consequently the remainder is computed exactly and |r| < |y|/2. But
drem(x,0) is exceptional; see below under DIAGNOSTICS. remainder is an
alternate entry point for drem. dreml is the long double counterpart of
drem.
The ceil functions return the smallest integer not less than x. The
argument x is double for ceil, long double for ceill, and float for fceil
and its ANSI-named equivalent ceilf.
The trunc functions return the integer (represented as a floating-point
number) of x with the fractional bits truncated. The argument x is
double for trunc, long double for truncl, and float for ftrunc.
fabs returns the absolute value of the double x, |x|. It also has
counterparts of type long double and float, namely fabsl, and fabsf,
respectively.
rint returns the integer (represented as a double precision number)
nearest its double argument x in the direction of the prevailing rounding
mode. rintl is the long double counterpart of rint. rint has no
counterpart which accepts an argument of type float.
fmod returns the floating-point remainder of the division of its double
arguments x by y. It returns a number f with the same sign as x, such
that x = iy + f for some integer i, and |f| < |y|. Hence both the
invocations
fmod(2.5,1.0)
fmod(2.5,-1.0)
yield 0.5, while the two invocations
fmod(-2.5,1.0)
fmod(-2.5,-1.0)
yield -0.5.
fmodl is the counterpart of fmod which accepts and returns values of type
long double and fmodf is the counterpart of fmod which accepts and
returns values of type float.
In the diagnostics below, functions in the standard math library libm.a,
are referred to as -lm versions, those in math library libmx.a are
referred to as -lmx versions, and those in the the BSD math library
libm43.a are referred to as -lm43 versions. The -lm and -lmx versions
always return the default Quiet NaN and set errno to EDOM when a NaN is
used as an argument. A NaN argument usually causes the -lm43 versions to
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FLOOR(3M) FLOOR(3M)
return the same argument. The -lm43 versions never set errno. The value
of HUGE_VAL is IEEE Infinity.
If y (and, possibly, x) are zero, or if x is +/-HUGE_VAL, the fmod
functions return a quiet NaN, and set errno to EDOM.
IEEE 754 defines drem(x,0) and drem(infinity,y) to be invalid operations
that produce a NaN.
A version of the double-precision fabs function exists in the C library
as well. The C library version may not behave correctly when the input
is NaN.
Long double operations on this system are only supported in round to
nearest rounding mode (the default). The system must be in round to
nearest rounding mode when calling any of the long double functions, or
incorrect answers will result.
Users concerned with portability to other computer systems should note
that the long double and float versions of these functions are optional
according to the ANSI C Programming Language Specification ISO/IEC 9899 :
1990 (E).
Long double functions have been renamed to be compliant with the ANSI-C
standard, however to be backward compatible, they may still be called
with the double precision function name prefixed with a q. (Exceptions:
functions fabsl and fmodl may be called with names qabs and qmod, resp.)
In the default rounding mode, round to nearest, rint(x) is the integer
nearest x with the additional stipulation that if |rint(x)-x|=1/2 then
rint(x) is even. Other rounding modes can make rint act like floor, or
like ceil, or round towards zero.
Another way to obtain an integer near x is to declare (in C)
double x; int k; k = x;
The C compilers round x towards zero to get the integer k. Also note
that, if x is larger than k can accommodate, the value of k and the
presence or absence of an integer overflow are hard to detect.
IEEE 754 requires copysign(x,Nan) = _x. In this implementation of
copysign, the sign of NaN is ignored. Thus copysign(x,_NaN) = +x, and
copysign(_NaN,x) = +NaN.
abs(3C), math(3M), matherr(3M)
Page 3
FLOOR(3I) Last changed: 1-6-98
FLOOR - Returns the greatest integer less than or equal to its
argument
FLOOR ([A=]a)
UNICOS, UNICOS/mk, and IRIX systems
Fortran 90
The FLOOR intrinsic function returns the greatest integer less than or
equal to its argument. It accepts the following argument:
a Must be of type real
FLOOR is an elemental function. The name of this intrinsic cannot be
passed as an argument.
On UNICOS systems, both execution speed and the number of bits used in
mathematical operations are affected when compiling with
f90 -O fastint, which is the default setting. For more information on
this, see the CF90 Commands and Directives Reference Manual,
publication SR-3901.
The result is a default integer. The result has value equal to the
greatest integer less than or equal to a. The result is undefined if
the target machine cannot represent this value in the default integer
type.
FLOOR(3.7) has the value 3. FLOOR(-3.7) has the value -4.
CF90 Commands and Directives Reference Manual, publication SR-3901
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
FLOOR(3I) Last changed: 1-6-98
FLOOR - Returns the greatest integer less than or equal to its
argument
FLOOR ([A=]a)
UNICOS, UNICOS/mk, and IRIX systems
Fortran 90
The FLOOR intrinsic function returns the greatest integer less than or
equal to its argument. It accepts the following argument:
a Must be of type real
FLOOR is an elemental function. The name of this intrinsic cannot be
passed as an argument.
On UNICOS systems, both execution speed and the number of bits used in
mathematical operations are affected when compiling with
f90 -O fastint, which is the default setting. For more information on
this, see the CF90 Commands and Directives Reference Manual,
publication SR-3901.
The result is a default integer. The result has value equal to the
greatest integer less than or equal to a. The result is undefined if
the target machine cannot represent this value in the default integer
type.
FLOOR(3.7) has the value 3. FLOOR(-3.7) has the value -4.
CF90 Commands and Directives Reference Manual, publication SR-3901
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
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