Let's say I want to differentiate a sum w.r.t. one of its terms. Below is a
trivial case, though my real case is more complex.
(%i1) expr : sum(x[i], i, 1, N);
N
====
\
(%o1) > x
/ i
====
i = 1
(%i2) diff(expr, x[1]);
(%o2) 0
(%i3)
Of course the answer I'm looking for is 1. I want Maxima to treat the
summation as if I had written out, for some fixed N:
expr : x[1] + x[2] + x[3] + ... + x[N];
How do I get Maxima to behave more intelligently w.r.t. subscripts?