# MATLAB: Find the sum of the non perimeter elements of a matrix using a for loop

loopmatrixnon perimetersum

I have this matrix
 B=[-3 4 7;9 11 -13;-17 19 -23;-29 31 37;39 41 47]
and I need to find the sum of the non perimeter elements using a for loop. I can find the sum of a single column or row or of the whole matrix, but I don't know how to write a loop to only sum the 3 non perimeter numbers. Any help is appreciated, thank you.

B=[-3 4 7;9 11 -13;-17 19 -23;-29 31 37;39 41 47][rows, columns] = size(B)theSum = 0;for col = 2 : columns - 1  for row = 2 : rows-1    theSum = theSum + B(row, col);  endendfprintf('The sum = %f\n', theSum);