MATLAB: Calculations or sum all diagonal elements

sum diagonal elements

hi. to sum all diagonal elements i used
sum(diag(a))
know; if i want to sum first 170 elements or last 80 elements, how can i do this.

Best Answer

FirstN = @(V,N) V(1:N);
LastN = @(V,N) V(end-N+1:end);
sum(FirstN(diag(a), 170))
sum(LastN(diag(a), 80))