multiplying certain parts of an 8x8 matrix

How do I sum the 4 corners and 4 middle numbers of an 8x8 magic matrix?

[Jan]

You mention a mutliplication in the subject, but ask for a sum in the body.

Answer 1

[Matt Fig]

M = magic(8)
S =  sum(M([1 8 57 64 28 29 36 37]))

[Jan]

You can get this solution if you look on: reshape(1:64, 8, 8)

Answer 2

[Walter Roberson]

sum( [M(1,1), M(1,end), M(end,1), M(end,end), reshape(M(floor(end/2):floor(end/2)+1,floor(end/2):floor(end/2)+1),1,[]) ])