This seems like a bug in lsum: gg : x^3+t*x^2-3*x-2*t$ lsum(gg*t,t,rootsof(t^2+1)); -> ?%lsum(gg*t,t,rootsof(t^2+1))$ Shouldn't gg be substituted? How can I do this? (The 1D display of lsum needs work too.) Ray