Round(3) User Contributed Perl Documentation Round(3)
NAME
Math::Round - Perl extension for rounding numbers
SYNOPSIS
use Math::Round qw(...those desired... or :all);
$rounded = round($scalar);
@rounded = round(LIST...);
$rounded = nearest($target, $scalar);
@rounded = nearest($target, LIST...);
# and other functions as described below
DESCRIPTION
Math::Round supplies functions that will round numbers in different ways. The functions round and nearest are exported by default; others
are available as described below. "use ... qw(:all)" exports all functions.
FUNCTIONS
round LIST
Rounds the number(s) to the nearest integer. In scalar context, returns a single value; in list context, returns a list of values.
Numbers that are halfway between two integers are rounded "to infinity"; i.e., positive values are rounded up (e.g., 2.5 becomes 3) and
negative values down (e.g., -2.5 becomes -3).
round_even LIST
Rounds the number(s) to the nearest integer. In scalar context, returns a single value; in list context, returns a list of values.
Numbers that are halfway between two integers are rounded to the nearest even number; e.g., 2.5 becomes 2, 3.5 becomes 4, and -2.5
becomes -2.
round_odd LIST
Rounds the number(s) to the nearest integer. In scalar context, returns a single value; in list context, returns a list of values.
Numbers that are halfway between two integers are rounded to the nearest odd number; e.g., 3.5 becomes 3, 4.5 becomes 5, and -3.5 becomes
-3.
round_rand LIST
Rounds the number(s) to the nearest integer. In scalar context, returns a single value; in list context, returns a list of values.
Numbers that are halfway between two integers are rounded up or down in a random fashion. For example, in a large number of trials, 2.5
will become 2 half the time and 3 half the time.
nearest TARGET, LIST
Rounds the number(s) to the nearest multiple of the target value. TARGET must be positive. In scalar context, returns a single value;
in list context, returns a list of values. Numbers that are halfway between two multiples of the target will be rounded to infinity.
For example:
nearest(10, 44) yields 40
nearest(10, 46) 50
nearest(10, 45) 50
nearest(25, 328) 325
nearest(.1, 4.567) 4.6
nearest(10, -45) -50
nearest_ceil TARGET, LIST
Rounds the number(s) to the nearest multiple of the target value. TARGET must be positive. In scalar context, returns a single value;
in list context, returns a list of values. Numbers that are halfway between two multiples of the target will be rounded to the ceiling,
i.e. the next algebraically higher multiple. For example:
nearest_ceil(10, 44) yields 40
nearest_ceil(10, 45) 50
nearest_ceil(10, -45) -40
nearest_floor TARGET, LIST
Rounds the number(s) to the nearest multiple of the target value. TARGET must be positive. In scalar context, returns a single value;
in list context, returns a list of values. Numbers that are halfway between two multiples of the target will be rounded to the floor,
i.e. the next algebraically lower multiple. For example:
nearest_floor(10, 44) yields 40
nearest_floor(10, 45) 40
nearest_floor(10, -45) -50
nearest_rand TARGET, LIST
Rounds the number(s) to the nearest multiple of the target value. TARGET must be positive. In scalar context, returns a single value;
in list context, returns a list of values. Numbers that are halfway between two multiples of the target will be rounded up or down in a
random fashion. For example, in a large number of trials, "nearest(10, 45)" will yield 40 half the time and 50 half the time.
nlowmult TARGET, LIST
Returns the next lower multiple of the number(s) in LIST. TARGET must be positive. In scalar context, returns a single value; in list
context, returns a list of values. Numbers that are between two multiples of the target will be adjusted to the nearest multiples of
LIST that are algebraically lower. For example:
nlowmult(10, 44) yields 40
nlowmult(10, 46) 40
nlowmult(25, 328) 325
nlowmult(.1, 4.567) 4.5
nlowmult(10, -41) -50
nhimult TARGET, LIST
Returns the next higher multiple of the number(s) in LIST. TARGET must be positive. In scalar context, returns a single value; in list
context, returns a list of values. Numbers that are between two multiples of the target will be adjusted to the nearest multiples of
LIST that are algebraically higher. For example:
nhimult(10, 44) yields 50
nhimult(10, 46) 50
nhimult(25, 328) 350
nhimult(.1, 4.512) 4.6
nhimult(10, -49) -40
VARIABLE
The variable $Math::Round::half is used by most routines in this module. Its value is very slightly larger than 0.5, for reasons explained
below. If you find that your application does not deliver the expected results, you may reset this variable at will.
STANDARD FLOATING-POINT DISCLAIMER
Floating-point numbers are, of course, a rational subset of the real numbers, so calculations with them are not always exact. Numbers that
are supposed to be halfway between two others may surprise you; for instance, 0.85 may not be exactly halfway between 0.8 and 0.9, and
(0.75 - 0.7) may not be the same as (0.85 - 0.8).
In order to give more predictable results, these routines use a value for one-half that is slightly larger than 0.5. Nevertheless, if the
numbers to be rounded are stored as floating-point, they will be subject, as usual, to the mercies of your hardware, your C compiler, etc.
AUTHOR
Math::Round was written by Geoffrey Rommel <GROMMEL@cpan.org> in October 2000.
perl v5.16.2 2006-11-21 Round(3)