On 2010-04-19 13:47-0700 Ed Zaron wrote: > Hi All,
> I've been using plplot for a project where we have to plot so-called "co-tidal charts" which display the amplitude and phase of the tide in the ocean. The amplitude is normally shown with a color image (made with plimage), and the phase is shown with contours (using the fortran interface, plcon1). > As you may know, contours of phase data have jumps where the phase wraps around, say, the 0/360 degree reference phase. This leads to situations in contour plots where the phase is contoured nicely, except where these jumps occur. Within the jump, all the contour lines are packed into the jump. This is an unavoidable consequence of trying to contour phase in 2-d, whenever the field has zero amplitude points (so-called, amphidromes, in the tidal context) where the phase is undefined. > I've attached a little patch to plplot/src/plcont.c from a freshly checked out source distribution (r10926). I wonder if you might consider adding a new subroutine to the plplot library, say, plcont_phase, which would correctly represent phase contours without the jumps? Hi Ed: I haven't looked at your patch, but I assume it processes phase data to impose phase continuity so that after processing you end up (in general) with a continous phase range from -M*360 deg to N*360 deg which is easy to contour. Assuming your patch does something like that, the question which I would like you to discuss further is whether this is of sufficient usefulness to PLplot users to add this functionality to our API for all the languages we support or whether this straightforward processing to impose phase continuity should be done by individual users before they call PLplot with their (now) continuous phase data. 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 __________________________ ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
