Thanks for the report. I confirm the bug in Sage 8.7.beta7. What is strange is that ddChi seems a perfectly valid symbolic expression: sage: ddChi = ddChi.expand(); ddChi 2*diff(chi(r, theta, phi), r)/r + cos(theta)*diff(chi(r, theta, phi), theta )/(r^2*sin(theta)) + diff(chi(r, theta, phi), theta, theta)/r^2 + diff(chi(r , theta, phi), phi, phi)/(r^2*sin(theta)^2) + diff(chi(r, theta, phi), r, r) sage: (ddChi - 2*diff(chi(r, theta, phi), r)/r).simplify() cos(theta)*diff(chi(r, theta, phi), theta)/(r^2*sin(theta)) + diff(chi(r, theta, phi), theta, theta)/r^2 + diff(chi(r, theta, phi), phi, phi)/(r^2*sin (theta)^2) + diff(chi(r, theta, phi), r, r)
and yet sage: ddChi.coefficient(diff(chi(r, theta, phi), r), 1) 0 Eric. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
