Following function will find out the center location of the given matrix mat. You can refer to the [row, col] values returned by it to find out the value at that location.
CAUTION : When one of the dimension of matrix is even, it will still find out the center which ideally do no exists. For the even dimension it will report the center point value to be the last value from the first half of the length in that dimension.
function [mid_row, mid_col] = findCenter(mat)
mid_row = floor((size(mat, 1) + 1) / 2);
mid_col = floor((size(mat, 2) + 1) / 2);