Math::Round(3) | User Contributed Perl Documentation | Math::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).
Starting in Perl 5.22, the POSIX module by default exports all functions, including one named "round". If you use both POSIX and this module, exercise due caution.

**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.

# COPYRIGHT AND LICENSE¶

This software is copyright (c) 2000 by Geoffrey Rommel <grommel@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

2024-03-08 | perl v5.38.2 |