[manual] suggested addition to pcolor description

[Petr Mikulik]

> > > >pcolor([1 2; 3 3])
> > > >shading interp
> > > >shading flat
> > > >
> > > >Therefore, I've written the following patch:
> > > >https://sourceforge.net/tracker/index.php?func=detail&aid=2558565&group_id=2055&atid=302055
> > > >[ 2558565 ] pm3d interpolate 0,0
> > > >The animated demo there shows color surface transformations; Octave would
> > > >use for its "shading interp" the option
> > > > set pm3d interpolate 0,0
> > >
> > >I think the attached files look good ... but can you describe what has been
> > >changed.  The results (in your email) look very similar to what the current
> > >gnuplot sources produce.
> >
> >It is desired to achieve higher resolution plot with an alternative "pm3d
> >interpolate" option. Let us suppose that "continuous" colour gradient on the
> >map/surface would need edge size of at least 200 pixels on screen window.
> >Then
> > a=hilb(4);
> > pcolor(a);
> >would need
> >	set pm3d interpolate 50,50
> >while
> > a=hilb(100);
> > pcolor(a);
> >would need
> > set pm3d interpolate 2,2
> >
> >With the new patch, you can set
> >	set pm3d interpolate -200,-200
> >and gnuplot will ensure at least 200 points in both cases, i.e. Octave
> >passes the sampling to the drawing backend.
> >
> >Currently,
> >	set pm3d interpolate 0,0
> >is equivalent to 200 points.
> 
> Ok, thanks for explaining.
> 
> I'll patch my gnuplot sources and work on a patch for Octave.
> 
> Are you looking for some of us to test drive your gnuplot patch, as well?

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.

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PM