Module: Combinatorics::Derange

Defined in:: lib/combinatorics/derange/mixin.rb,
lib/combinatorics/derange/cardinality.rb

Defined Under Namespace

Modules: Mixin

Class Method Summary collapse

.cardinality(n) ⇒ Object
Compute the number of derangements for a data structure of given size.
.D(n) ⇒ Object
Wrapper for derangement cardinality method defined above.

Class Method Details

.cardinality(n) ⇒ `Object`

Compute the number of derangements for a data structure of given size

See Also:

Math.subfactorial



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# File 'lib/combinatorics/derange/cardinality.rb', line 10

def self.cardinality(n)
  Math.subfactorial(n)
end

.D(n) ⇒ `Object`

Note:

The letter `D' is academic representation for derangements

Wrapper for derangement cardinality method defined above



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# File 'lib/combinatorics/derange/cardinality.rb', line 19

def self.D(n)
  cardinality(n)
end