Quick Navigator

 Search Site Miscellaneous Server Agreement Year 2038 Credits

# Manual Reference Pages  -  MATH::ROUND (3)

.ds Aq ’

### 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

<B>Math::RoundB> supplies functions that will round numbers in different ways. The functions <B>roundB> and <B>nearestB> are exported by default; others are available as described below. use ... qw(:all) exports all functions.

### FUNCTIONS

 roundB> 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_evenB> 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_oddB> 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_randB> 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. nearestB> 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_ceilB> 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_floorB> 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_randB> 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. nlowmultB> 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 ``` nhimultB> 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 <B>B>\$Math::Round::half<B>B> 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.
Search for    or go to Top of page |  Section 3 |  Main Index

 perl v5.20.3 ROUND (3) 2015-01-02

Visit the GSP FreeBSD Man Page Interface.
Output converted with manServer 1.07.