matrix_perimeter

Function matrix_perimeter extracts the outer elements of a matrix in a clockwise sense.

This is a utility function.
It may be used for matrix decompositions or extraction of boundaries in 2d rectangular domains.
INPUTS
------
A = An n x m matrix (real or imaginary)
OUTPUTS
-------
x = Row vector of the elements of the matrix that exist in the perimeter, taken in a clockwise sense

A = An (n-2)x(m-2) matrix, same as input matrix, without its elements existed in the perimeter (The input matrix is decomposed within the function)

COMPATIBILITY
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Matlab 7.2 and later

EXAMPLE
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>> A=magic(4)

A =

16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1

>> [x,B]=matrix_perimeter(A)

x =

16 2 3 13 8 12 1 15 14 4 9 5

B =

11 10
7 6