JacobianMatrix[pt] gives the Jacobian matrix of the transformation from the default coordinate system to the Cartesian coordinate system at the point pt.
gives the Jacobian matrix of the transformation from the coordinate system coordsys to the Cartesian coordinate system at the point pt.
The Jacobian matrix consists of the elements where are the Cartesian coordinates and are the coordinates of the coordinate system coordsys, if specified, or the default coordinate system otherwise.
The coordinates of pt should be given in the coordinate system coordsys, if specified, or the default coordinate system otherwise.
If pt is not given, the default coordinate variables for coordsys are used.