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FACTORADIC

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FACTORADIC

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22 Feb 2009 (Updated )

Obtain the factorial radix representation of a number.

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Description

F = factoradic(M,N) returns the conversion of integer M into factorial radix. F is a 1-by-N vector. The factoradic is also known as the Lehmer Code. The factoradic of M is best understood by example.

            Example: 89 = 3x4! + 2x3! + 2x2! + 1x1! + 0x0!
                    therefore factoradic(89,5) = (3,2,2,1,0)
    
    M must lie in the range [0 : N!-1].
    Leading zeros will be present in F when M < (N-1)!-1.

           Example: factoradic(19,6) = (0,0,3,0,1,0)

A practical use of the factoradic is the generation of permutations. See ONEPERM on the File Exchange.

MATLAB release MATLAB 7 (R14)
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Comments and Ratings (1)
28 Apr 2009 John D'Errico

A useful tool when generating permutations. In fact, I was thinking of putting up this myself. No need to do so now.

Good help. Error checks. Simple engine.

Updates
27 Apr 2009

Thanks to Stefano Bolli for noticing a typo in the error-checking.

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