Hello!
[Using Maxima 5.17.0 provided by the rpm 5.17.0-1.3 for openSuSE]
Please, have a look at this.
These sums are correct:
(%i27) sum(k, k, 1, 4);
(%o27) 10
(%i28) sum(-k, k, -4, -1);
(%o28) 10
Now check these two sums:
(%i1) simpsum: true;
(%o1) true
(%i2) sum(k, k, 1, a);
2
a + a
(%o2) ------
2
(%i3) sum(-k, k, -a, -1);
Is a positive, negative, or zero?
p;
2
a - a
(%o3) ------
2
(%i4) sum(-k, k, -a, -1);
Is a positive, negative, or zero?
n;
2
- a + (- a - 1) - 1
(%o4) --------------------
2
(%i5) ratsimp(%);
2
a + a
(%o5) ------
2
Should n't a positive "a" create the same result as %o2 and a negative
the empty sum, thus 0? Do I miss something?
Best Regards
Alexandros