A = input('Please input the matrix like "[1, 2; 3, 4]":');
% Type e.g.:
% [1, 2; 3, 4]
meanA = mean(A(:))
% Or in modern Matlab versions:
meanA = mean(A, 'all')
% Or more basic:
meanA = sum(A, 'all') / numel(A)
See:
doc input
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!