This bug is due to a limit bug:
(%i38) e : (2*sin(x)*z+cos(x)*sin(2*x)-2*cos(x)^2*sin(x))/(z^2+(-sin
(2*x)^2-4*sin(x)^2-cos(x)^2-1)*z+sin(2*x)^2-4*cos(x)*sin(x)*sin(2*x)+4*cos
(x)^2*sin(x)^2);
(%o38) (2*sin(x)*z+cos(x)*sin(2*x)-2*cos(x)^2*sin(x))/(z^2+(-sin
(2*x)^2-4*sin(x)^2-cos(x)^2-1)*z+sin(2*x)^2-4*cos(x)*sin(x)*sin(2*x)+4*cos
(x)^2*sin(x)^2)
Bogus:
(%i39) limit(e,z,0);
(%o39) cos(x)/(sin(2*x)-2*cos(x)*sin(x))
(%i40) trigexpand(%);
Division by 0 -- an error. To debug this try debugmode(true);
Correct, I think:
(%i41) limit(trigexpand(e),z,0);
(%o41) -(2*sin(x))/((4*cos(x)^2+4)*sin(x)^2+cos(x)^2+1)
(%i42) trigexpand(%);
(%o42) -(2*sin(x))/((4*cos(x)^2+4)*sin(x)^2+cos(x)^2+1)
Barton
-----maxima-bounces at math.utexas.edu wrote: -----
>This?seems?to?work?nicely?except?for?one?very?big?problem:?it?does?not
>check?for?expression?zero?equivalence?except?syntactically.??See?below?for
>an?example.
>
>??????????????-s
>