>which doesn't match the output shown in lorentz_example.txt, namely > > 'diff(b3,z,1)*Dx*Dy*Dz+'diff(b2,y,1)*Dx*Dy*Dz+'diff(b1,x,1)*Dx*Dy*Dz > >Is there an error in the input? If I replace b22 with b2 in the input, >then I get the output shown in lorentz_example.txt. OOPS! b2 is correct. thanks Robert Gosei Furuya