Contouring based on code published in Javatech, Volume 13 Issue 9, "Contour Plotting In Java" by David Rand. This code is based on Fortran code implementing 1978 article by W. V. Snyder. W. V. Snyder, "Algorithm 531, Contour plotting [J6]," ACM Trans. Math. Softw. 4, 3 (Sept. 1978), 290-294.
returns a rank 2 dataset, a bundle dataset, listing the points of the contour paths. The dataset will be ds[n,3] where the bundled datasets are: [x,y,z] and where DEPEND_0 indicates the step number. Jumps in the step number indicate a break in the contour.