🚀 go-pugleaf

Dan Cook="uncle dan"=dcook@garnet.berkeley.edu writes:

>I'm still looking for a contour plotting package... I have
>gotten two possibles from several responses... contour and
>gnuplot, both of which may be wonderful packages, but alas
>they lack the ability to plot contours for a set of x,y,z
>data which is not evenly spaced on a rectangular grid...
>Part of my problem is that not all of my data is evenly
>spaced, so I can't really get what I need from either of
>these two programs... If anyone has any other ideas, please
>let me know...

If you are working on a UNIX workstation, I highly recommend The 
"Generic Mapping Tools (GMT)-SYSTEM plotting package 
by Paul Wessal & Walter Smith. This outstanding package solves many 
of the common gridding and map projection problems encountered when 
making contour/gray-scale maps and scatter plots. The "surface" program 
in GMT uses a continuous curvature gridding algorithm to grid arbitrarily 
spaced data like you describe. You can then use the "grdcontour" program 
to contour the data, not to mention many other useful plotting options.
The reference they quote for the gridding algorithm used in GMT/surface is:

     Smith, W. H. F, and P. Wessel, 1990, Gridding with  continu-
     ous curvature splines in tension, Geophysics, 55, 293-305.

You can obtain GMT via anonymous ftp from kiawe.soest.hawaii.edu 
(128.171.151.16). Good luck.

-Joe Mazz