If you run examples/c/x16c -dev xwin -exclude -nx 20 -ny 20
a smooth donut is excluded from the 5th page (as expected, since years ago Rafael modified the defined algorithm for plshade(s) to give smooth edges using some sort of iterative technique). However, if you use coarser resolutions, e.g., examples/c/x16c -dev xwin -exclude -nx 10 -ny 10 Rafael's iteration sometimes still gives reasonably good results (some edges of the donut are smooth) at coarser resolutions but also sometimes gives horrible results (the edges of the donut are extremely misplaced or missing altogether). I interpret these results as a numerical robustness issue (a starting solution that is so bad that it cannot converge, or a convergence criterion that stops the iteration before it has converged). I also just ran into the same problem with the software fallback (using plshades) for plgradient. 2x2 points should perfectly determine the plane representing the gradient, but the edge of the defined region was completely erratic at that resolution, and I had to use a severely redundant 20x20 resolution to get robust smooth results for the edges of the defined region represented by a polygon. In the interests of speed I far prefer using 2x2 resolution to represent the gradient plane for the plgradient plshades fallback so I will look into this numerical robustness issue. If I can solve it, I expect to get smooth edge results at 2x2 resolution not only for example 16, but also for the plshades fallback for plgradient. Alan __________________________ Alan W. Irwin Astronomical research affiliation with Department of Physics and Astronomy, University of Victoria (astrowww.phys.uvic.ca). Programming affiliations with the FreeEOS equation-of-state implementation for stellar interiors (freeeos.sf.net); PLplot scientific plotting software package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project (lbproject.sf.net). __________________________ Linux-powered Science __________________________ ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
