Bugfix for GosperSum? (was: cannot load Zeilberger)



Blindly changing

if op(expr) = "+"  then

into

if op(expr) = "+"  or op(expr)="-" then

near the end of the function

shiftQuoHypCheckAux(expr,k,hyp_flag)

in zeilberger/shiftQuotient.mac

seems to fix this bug.

I didn't do much testing. Are there any regression tests around for
zeilberger?

Michel