Are you expecting polarform to simplify its arg? Otherwise, I kind of think this is expected.
(%i1) polarform(cos(x)^2 + sin(x)^2-1);
(%o1) %e^(%i*atan2(0,sin(x)^2+cos(x)^2-1))*abs(sin(x)^2+cos(x)^2-1)
(%i2) trigsimp(%);
atan2: atan2(0,0) is undefined.
Raymond Toy
2012-10-06
Are you expecting polarform to simplify its arg? Otherwise, I kind of think this is expected.