progress on diff(sum) and sum(kron_delta)



Robert Dodier <robert.dodier <at> gmail.com> writes:

> I think I've made some progress on computing derivatives
> of sums and sums of kron_delta. It is doubtless possible
> to find bugs in this but all the same I think it's an improvement.
>

It is very useful already! Is it possible to deal with dot operator?

display2d : false $
load ("sum_kron_delta.mac") $
assume(i<=n) $
assume(i>=1) $
declare(i, integer) $
declare([a, b], nonscalar) $
expr: (kron_delta(i, j)*a[i]) . b[i]$
'sum (expr, j, 1, n) ;
''%;

(%o41) 'sum((a[i]*kron_delta(i,j)) . b[i],j,1,n)