I guess cos(k+q)-cos(k) = -2*sin(k+q/2)*sin(q/2)
now, how do I get sage to trafo the lhs into the rhs (and where would I have found this in the documentation) ? Thanks, wb -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
