i need to pad my matrix only from the ends like this picture

[Bruno Luong]

What represent the three colors?

Answer 1

[DGM]

You should be able to use padarray() to pad with constant values.

A = magic(5)

A = 5×5

17 24 1 8 15 23 5 7 14 16 4 6 13 20 22 10 12 19 21 3 11 18 25 2 9

Apadded = padarray(A,[3 3],0,'post')

Apadded = 8×8

17 24 1 8 15 0 0 0 23 5 7 14 16 0 0 0 4 6 13 20 22 0 0 0 10 12 19 21 3 0 0 0 11 18 25 2 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

In this example, [3 3] specifies the pad width in each dimension. The pad value is 0, and 'post' specifies that only the trailing edge gets padded in either dimension.