[Maxima] do not expand sums explicitly

[Soegtrop, Michael]

Dear Dmitry,

you could later force the evaluation of the sum by ev(expr, simpsum).

result: factor(sum(diff(ev(expr,simpsum),a[j])*c[j],j,1,3));

%e^(a[3]*b[3]+a[2]*b[2]+a[1]*b[1])*(b[3]*c[3]+b[2]*c[2]+b[1]*c[1])

But I agree that it would be convenient, if maxima would be able to evaluate the differentiation, especially if the sum limits are not explicit.

Best regards,

Michael