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FACTORADIC

version 1.1 (1.77 KB) by

Obtain the factorial radix representation of a number.

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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.

Comments and Ratings (1)

John D'Errico

John D'Errico (view profile)

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

1.1

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

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MATLAB 7 (R14)

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