plsurf() bugs [Was: Re: [Plplot-devel] valgrind warning generated by this line, why?]

[<jc...@fe...>]

On Thursday 17 October 2002 05:16, Alan W. Irwin wrote:
| On Wed, 16 Oct 2002, Alan W. Irwin wrote:
| > The tcl example 8 result is different from the C and python result.
| > I will look further at that since it may be something simple.
|
| ifshade=3D=3D2 was creating some differences, and that was due to a bug
| in tclAPI.c (clev =3D NULL rather than *clev =3D NULL) which I have now
| fixed.
|
| The results of the diff command for various combinations of ifshade
| range indicate the only remaining differences are for ifshade=3D=3D5.
| This is the page that uses contours where Joao created the levels
| following Vince's suggestion for preserving as much precision as
| possible for the current 12-digit rounding scheme.  Probably the only
| solution here is to use tcl native double precision (or single
| precision when appropriate) rather than converting strings to double
| and back rounded to 12 digits.  I am looking forward to Maurice
| implementing this just so we don't continue to have these minor but
| still somewhat lame tcl differences compared to every other front
| end.
|
| Joao, I have noticed one final plsurf3d core bug that shows up for
| all front ends and which detracts from the appearance of the surface
| contours; those contour lines are sometimes broken (page 6 for
| example).

I supose you are refering to the contour drawn at the surface, using the=20
rosenbrock function?

If you mean the sombrero like function, than try to magnify the broken=20
contour line using the tk driver. The contour is there!

If you mean the rosenbrock function, and you mean that some contour=20
lines in the deep valeys are broken, remember that you are watching=20
just the face of the valey that is visible... thus you can only see=20
part of the contour.

To make the valeys more visible, you can try to increase the number of=20
points, XPTS and YPTS. I did it and got a core dump!!! One more bug to=20
solve.

Joao

|  You comment in the code that the surface contours are
| simple minded.  Does that mean it will be difficult to fix the broken
| surface contour problem?
|
| Alan
|
|
|
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