petsc-3.14.6 2021-03-30
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Encode a permutation of n into an integer in [0, n!). This inverts PetscDTEnumPerm.

Input Arguments

n - a non-negative integer (see note about limits below)
perm - the permuted list of the integers [0, ..., n-1]

Output Arguments

k - an integer in [0, n!)
isOdd - if not NULL, returns wether the permutation used an even or odd number of swaps.

Note: this is limited to n such that n! can be represented by PetscInt, which is 12 if PetscInt is a signed 32-bit integer and 20 if PetscInt is a signed 64-bit integer.




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