% euler angles, theta in [0 2pi), phi in [0 pi)

function tensor = gTensor3(e1, e2, v1)
tensor = [e1 0 0; 0 e2 0; 0 0 e2];
v2 = rand(3,1);
v2 = v2-(v1'*v2)*v1;
v2 = v2/norm(v2);
v = [v1, v2, cross(v1,v2)];
tensor=v*tensor*v';