ruby-pretty-round

This gem add useful numerical rounding methods to Numeric class as shown below.

• round to nearest multiple
• round with significant digits

Install

$ gem install pretty_round

Usage

require "pretty_round"

x = 123.456

# round with precision
x.roundup #=> 124
x.rounddown(2) #=> 123.45

# round to nearest multiple
x.mceil(50) #=> 150
x.mfloor(25) #=> 100
x.mroundup(2) #=> 124
x.mrounddown(0.3) #=> 123.3
x.mround(9.87) #=> 128.31

# round with significant digit
x.sceil(1) #=> 200
x.sfloor(2) #=> 120
x.sroundup(3) #=> 124
x.srounddown(4) #=> 123.4
x.sround(5) #=> 123.46

Refinements

When require 'pretty_round', rounding methods are included in global scope. To include in limited scope, please load pretty_round/core and use refinements.

require 'pretty_round/core'
using PrettyRound

Rounding direction

• #*ceil / #*floor: These methods round to the positive / negative infinity direction. Its behavior is same as built-in #ceil, #floor.
• #*roundup / #*rounddown: These methods round to far from / near to 0 direction.
• #*round: These methods round off the absolute value, does not round even. Its behavior is same as built-in #round.
• #*truncate: These methods are alias of #*rounddown.

Result table is shown below, including ruby built-in rounding methods for comparison. An axis of abscissas refers to the receiver and an axis of ordinates refers to the methods.

              |  1.9  1.1 -1.1 -1.9
-----------------------------------
.ceil         |    2    2   -1   -1 (ruby built-in)
.floor        |    1    1   -2   -2 (ruby built-in)
.roundup      |    2    2   -2   -2
.rounddown    |    1    1   -1   -1
.round        |    2    1   -1   -2 (ruby built-in)
.truncate     |    1    1   -1   -1 (ruby built-in)
.mceil(1)     |    2    2   -1   -1
.mfloor(1)    |    1    1   -2   -2
.mroundup(1)  |    2    2   -2   -2
.mrounddown(1)|    1    1   -1   -1
.mround(1)    |    2    1   -1   -2
.mtruncate(1) |    1    1   -1   -1
.sceil(1)     |    2    2   -1   -1
.sfloor(1)    |    1    1   -2   -2
.sroundup(1)  |    2    2   -2   -2
.srounddown(1)|    1    1   -1   -1
.sround(1)    |    2    1   -1   -2
.struncate(1) |    1    1   -1   -1

Also, try to run examples/example.rb

Known Bugs

Float presision

1.2.mrounddown(0.1) #=> 1.1

Oops... Resulting 1.2 is expected.

Becouse,

1.2.divmod(0.1) #=> [11, 0.0999999999999999]

To avoid this bug, please use Rational.

1.2r.mrounddown(0.1r) #=> (6/5)