# nsum(y,x,a,b) is the numeric sum y as x from a to b; nsum(y_) := nsum(y,x,1,5,1); nsum(y_,x_) := nsum(y,x,1,5,1); nsum(y_,x_,b_) := nsum(y,x,0,b,1); nsum(y_,x_,a_,b_) := nsum(y,x,a,b,1);