numtoperm

["Jon Perry" <perry@globalnet.co.uk>]

3.2.33 numtoperm(n; k): generates the k-th permutation (as a row vector of
length n) of the
numbers 1 to n. The number k is taken modulo n! , i.e. inverse function of
permtonum.

numtoperm(5,0) returns [5,4,3,2,1] which is the k-th permutation of n to 1.

Also, how is this function defined, as:

? alias(np,numtoperm)
? np(5,0)
%3 = [5, 4, 3, 2, 1]
? np(5,1)
%2 = [5, 4, 3, 1, 2]
? np(5,2)
%4 = [5, 4, 2, 3, 1]
? np(5,3)
%5 = [5, 4, 1, 3, 2]
? np(5,4)
%6 = [5, 4, 2, 1, 3]
? np(5,5)
%7 = [5, 4, 1, 2, 3]

seems erratic. Surely an alphabetic ordering is preferable?

See http://www.users.globalnet.co.uk/~perry/maths/fld/fld.htm for
inspiration, etc...

Jon Perry
perry@globalnet.co.uk
http://www.users.globalnet.co.uk/~perry/maths
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