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MAT C=PERM(A,P)  / If P is a column vector (m*1) consisting of numbers
                   1,2,...,m in any order, the rows of A will be
                   permuted according to P.
                   If P is a row vector, the columns of A are permuted.
In fact P may contain any distinct numbers. The rows (or columns) of A
are permuted according to the magnitudes of these numbers.
There is another form of this operation
MAT C=PERM2(A,P) which does the same job but the permutation defined
by P is interpreted in a different way.
Let                          A=[1,2,3,4,5,6,7,8]
and                          P=[5,8,1,3,7,6,4,2].
Then MAT C=PERM(A,P)  gives  C=[3,8,4,7,1,6,5,2], i.e. C(P(i))=A(i),
but  MAT C=PERM2(A,P) gives  C=[5,8,1,3,7,6,4,2], i.e. C(i)=A(P(i)).

MAT C=PERM0(A,P) works as PERM2 but assumes that P really consists
of integers 1,2,... in some order. PERM0 is faster than PERM2.

  M = More information on MAT operations