[manual] suggested addition to pcolor description

[Petr Mikulik]

> >Yes, please try to patch both gnuplot and Octave and tell me whether it
> >gives the desired image.
> >
> >Note that
> >   set pm3d interpolate 0,0
> >can always be issued by Octave because current versions of gnuplot
> >silently ignore non-positive numbers.
> 
> Ok, I've made a local change to __go_draw_axes__.m and produce some images
> with both Octave+Gnuplot as well as Matlab.
> 
> Those interested can see them at the link below.
> 
> 	http://www.picturehosting.com/gallery.php?u=bpabbott&g=pm3d
> 
> Those who would like to exercise this functionality will need to apply Petr's
> patch to the developer's sources for gnuplot, and apply the attached changeset
> to the developers sources for Octave.

The patch should be:
    if (doing_interp_color)
      interp_str = "interpolate 0,0";
    else

If you find this resolution being (very) different from Matlab, then use
      interp_str = "interpolate -300,-300"; 
or some other negative numbers. Currently the default "0,0" is equivalent to 
"-200,-200".

> 	surf(peaks)
> 	colormap(jet(200))
> 	shading interp
> 
> After  an unpleasant delay a nice image was produced. Checking my Mac OSX
> activity monitor it appears that gnuplot requires 750MB of real memory and
> 2.5GB of virtual memory to produce this image. It is due to the excessive
> time and memory requiried that I decided to limit the levels of interpolation
> that occur across a particular quadrangle.

I don't wonder if the current changeset produced something like
	interpolate 90,90
i.e. drawing image with (200*90)^2 = 18000^2 points.

---
Petr Mikulik