  Dynamics of spiral galaxies derived from a given surface mass density has
been derived earlier in a classic paper. We try to transform the singular
elliptic function in the integral into a compact integral with regular elliptic
function. Solvable models are also considered as expansion basis for RC data.
The result makes corresponding numerical evaluations easier and analytic
analysis possible. It is applied to the study of the dynamics of Newtonian
system and MOND as well. Careful treatment is shown to be important in dealing
with the cut-off of the input data.
