How can I add three columns and three rows to a defined matrix?

I have a matrix 590x590 and I have to add three intermediate colomuns and three intermediate rows between the first and the second column/row of the original matrix and then other three rows and columns between the third and the fourth and so on. In other words I have to obtain a new matrix whose size is 1770x1770. How can I do it?

[Torsten]

And the lengths of the inserted rows/columns change from time to time to keep the complete matrix square ?

E.g. the rows/columns that you add in the second step between the third and the fourth row/column of the original matrix (or between the third and the fourth row/column of the matrix you obtained from the first step ?) should already have length 593.

Maybe you should give a small example for clarification.

[federica incatasciato]

No. They should have the same length. What I mean is:

column 1 x x x column 2 x x x column 3 ...

row1

s

s

s

row2

s

s

s

row3

...

Where x are the added columns and s are the added rows

Answer 1

[Image Analyst]

Try

newMatrix = imresize(oldMatrix, [1770, 1770]);