code: def drdcyl(r, lon, z):
      
      r = ctypes.c_double(r)
      lon = ctypes.c_double(lon)
      z = ctypes.c_double(z)
      jacobi = stypes.emptyDoubleMatrix()
      libspice.drdcyl_c(r, lon, z, jacobi)
      return stypes.cMatrixToNumpy(jacobi)
docs: This routine computes the Jacobian of the transformation from
      cylindrical to rectangular coordinates.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/drdcyl_c.html
  
      :param r: Distance of a point from the origin.
      :type r: float
      :param lon: Angle of the point from the xz plane in radians.
      :type lon: float
      :param z: Height of the point above the xy plane.
      :type z: float
      :return: Matrix of partial derivatives.
      :rtype: 3x3-Element Array of floats