Logged In: YES

user_id=501686

nusum is superseded by the more recent and extensive

Zeilberger package (share/contrib/Zeilberger) which includes

Gosper's algorithm as a special case.

Be that as it may, it turns out GosperSum in the Zeilberger

package has exactly the same defect ...

load ("Zeilberger/LOADZeilberger.mac");

GosperSum (x^k, k, 1, inf);

=> x^(inf+1)/(x-1)-x/(x-1)

I am guessing that the algorithm is phrased in terms of "n"

and there is no check to ensure that n is finite. If I'm not

mistaken the Zeilberger/Gosper stuff is advertised generally

as "indefinite summation" so that's understandable, but if

so then the Maxima fcns should make an effort to rule out

inapplicable cases.

I don't think it's worthwhile to fix nusum -- I think any

effort on this problem should be directed to the Zeilberger

package.

best,

Robert Dodier