Re: Gnuplot logarithmic contours and palette

[Ethan M. <merritt@u.washington.edu>]

On Tuesday 22 March 2005 11:15 am, Aapo Lankinen wrote:
>
> ---- clip ----
> unset surface
> set contour
> set logscale z
> set palette model HSV functions gray, gray, 1.0-0.5*gray
> set log cb
> unset colorbox
> set cntrparam levels 30
> set view 0,0
> splot x**2+y**2+1.0 palette
> ---- clap ----
>
> all the contour label lines in the legend have the same colour 
> as the maximum intensity contour line.  
> Can someone confirm?

I confirm there's a bug.

When cb is in logscale, the axis limits CB_AXIS.min and CB_AXIS.max
are stored as the log of the limit value. But the function cb2gray(val)
checks val itself against the limits, rather than checking log(val).

Unfortunately, changing it to log(val) inside cb2gray does not
produce the correct contour coloring either.  So there must be additional
problems.

There's ongoing discussion of revising the contouring code anyhow,
so maybe someone will spot the correct fix while revising it for
other reasons.

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington 98195-7742