4 Non-integral techniques for folding rotation curves

Prior to developing the method described in detail herein, various other methods were tried, and these shared the common property of being non-integral methods. That is, they attempted the process of folding by minimizing functionals defined by various forms of direct comparison of the velocity distributions on the approaching and receding sides of the spiral.

Whilst each of these various methods always folded some rotation curves successfully, they also each had high failure rates. The basic problem with such methods is that functionals defined over noisy data (which rotation curve data is) do not always display the mathematical properties of minimum points - even when in the close neighbourhood of such points. The results obtained with one obvious method in this class are briefly described in Appendix A.