Programming Ruby

The Pragmatic Programmer's Guide
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class Numeric
Parent: Object
Version: 1.6

Index:

+@ --@ abs coerce divmod eql? integer? modulo nonzero? remainder zero?


Subclasses: Float, Integer

Numeric is the fundamental base type for the concrete number classes Float, Fixnum, and Bignum.
mixins
Comparable: <, <=, ==, >=, >, between?

Difference between modulo and remainder. The modulo operator (``%'') always has the sign of the divisor, whereas remainder has the sign of the dividend.

a b a.divmod(b) a / b a.modulo(b) a.remainder(b)
13 4 3, 1 3 1 1
13 -4 -4, -3 -4 -3 1
-13 4 -4, 3 -4 3 -1
-13 -4 3, -1 3 -1 -1
11.5 4 2.0, 3.5 2.875 3.5 3.5
11.5 -4 -3.0, -0.5 -2.875 -0.5 3.5
-11.5 4 -3.0, 0.5 -2.875 0.5 -3.5
-11.5 -4 2.0, -3.5 2.875 -3.5 -3.5

instance methods
+@ +num -> num

Unary Plus---Returns the receiver's value.

--@ --num -> aNumeric

Unary Minus---Returns the receiver's value, negated.

abs num.abs -> aNumeric

Returns the absolute value of num.

12.abs » 12
(-34.56).abs » 34.56
-34.56.abs » 34.56

coerce num.coerce( aNumeric ) -> anArray

If aNumeric is the same type as num, returns an array containing aNumeric and num. Otherwise, returns an array with both aNumeric and num represented as Float objects.

1.coerce(2.5) » [2.5, 1.0]
1.2.coerce(3) » [3.0, 1.2]
1.coerce(2) » [2, 1]

divmod num.divmod( aNumeric ) -> anArray

Returns an array containing the quotient and modulus obtained by dividing num by aNumeric. If q, r = x.divmod(y),
q = floor(float(x) / float(y))
x = q * y + r

The quotient is rounded toward -infinity. See Table 22.6 on page 350.

11.divmod(3) » [3, 2]
11.divmod(-3) » [-4, -1]
11.divmod(3.5) » [3.0, 0.5]
(-11).divmod(3.5) » [-4.0, 3.0]
(11.5).divmod(3.5) » [3.0, 1.0]

eql? num.eql?( aNumeric ) -> true or false

Returns true if num and aNumeric are the same type and have equal values.

1 == 1.0 » true
1.eql?(1.0) » false
(1.0).eql?(1.0) » true

integer? num.integer? -> true or false

Returns true if num is an Integer (including Fixnum and Bignum).

modulo num.modulo( aNumeric ) -> aNumeric

Equivalent to num.divmod( aNumeric )[1].

nonzero? num.nonzero? -> num or nil

Returns num if num is not zero, nil otherwise. This behavior is useful when chaining comparisons:

a = %w( z Bb bB bb BB a aA Aa AA A )
b = a.sort {|a,b| (a.downcase <=> b.downcase).nonzero? || a <=> b }
b » ["A", "a", "AA", "Aa", "aA", "BB", "Bb", "bB", "bb", "z"]

remainder num.remainder( aNumeric ) -> aNumeric

If num and aNumeric have different signs, returns mod-aNumeric; otherwise, returns mod. In both cases mod is the value num.modulo( aNumeric ). The differences between remainder and modulo (%) are shown in Table 22.6 on page 350.

zero? num.zero? -> true or false

Returns true if num has a zero value.

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Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"
Copyright © 2000 Addison Wesley Longman, Inc. Released under the terms of the Open Publication License V1.0.
This reference is available for download.