Re: contourf

[Paul Kienzle]

On Apr 4, 2006, at 6:10 AM, Alexandre Ribeiro wrote:

> Hi
>
> I'm in trouble! In MatLab contourf is similar to contour, the only 
> diference is that the first one is filled. In octave contourf is not 
> working. I always have an error message.
>
> Tanks for your help
>
> Alexandre
>
> octave:50> x=rand(10,10);
> octave:51> contour(x)
> octave:52> contour(x,5)
> octave:53> contourf(x,5)
> error: expecting integer index, found 13.600000
> error: evaluating argument list element number 1
> error: called from `contourf' in file 
> `/usr/share/octave/site/m/octave-forge/plot/contourf.m'

contourf is an imaging hack.  It's kind of cute, but without gnuplot4.1 
which allows you to draw images with axes is is not very useful.  If it 
were in use this bug would have been fixed long ago.

The following patch fixes the bug.

Try the following:

        C=colormap;colormap(rand(64,3));contourf(peaks(200));colormap(C);

- Paul

*** contourf.m  27 Nov 2002 08:40:11 -0000      1.3
--- contourf.m  5 Apr 2006 10:30:03 -0000       1.4
*************** function contourf(z,n,w)
*** 36,42 ****
    z(z!=fix(z)) = 0;

    ## plot the image, with the contours drawn in black.
!   colormap([0,0,0; C(linspace(1,rows(C),n+1),:)]);
    image(flipud(z)+1);

    ## restore the colormap
--- 36,42 ----
    z(z!=fix(z)) = 0;

    ## plot the image, with the contours drawn in black.
!   colormap([0,0,0; C(round(linspace(1,rows(C),n+1)),:)]);
    image(flipud(z)+1);

    ## restore the colormap



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