# partialsum1(y,k,0,n) is partial sum of y index k from 1 to n ; partialsum1(y_,k_,a_,b_):= sum(y,k,a,b); partialsum1(y_,k_,b_):= sum(y,k,1,b); partialsum1(y_,k_):= sum(y,k,1,n); partialsum1(a_+b_,k_):= partialsum1(a,k)+partialsum1(b,k); partialsum1(y_):=sum(y,k,1,n);