IPERMUTE IPERMUTE Array Inverse Permutation Function

Usage

The ipermute function rearranges the contents of an array according
to the inverse of the specified permutation vector.  The syntx for 
its use is

   y = ipermute(x,p)

where p is a permutation vector - i.e., a vector containing the 
integers 1...ndims(x) each occuring exactly once.  The resulting
array y contains the same data as the array x, but ordered
according to the inverse of the given permutation.  This function and
the permute function are inverses of each other.
