bug concatenating vectors in 3.1.51+

[Jaroslav Hajek]

On Sun, Oct 12, 2008 at 8:59 PM, Ben Abbott <bpabbott at mac.com> wrote:
> I attempted a fresh build last night. My tip is
>
> changeset:   8210:a10397d26114
> tag:         tip
> user:        John W. Eaton <jwe at octave.org>
> date:        Fri Oct 10 15:10:58 2008 -0400
> summary:     graphics.cc (base_graphics_properties::adopt): place new
> child at front of list, not end; make children a column vector instead
> of a row vector
>
> The bug is fairly easy to see
>
>        [ones(1,0); zeros(5,1)]
>        error: number of columns must match (1 != 0)
>
> In Matlab
>
>  >> [ones(1,0);zeros(5,1)]
>
> ans =
>
>      0
>      0
>      0
>      0
>      0
>
> Presently Octave will not build for me.
>
> if [ -f gplot.eps ] ; then gs -dBATCH -dEPSCrop -dNOPAUSE -q -
> sDEVICE=pdfwrite -sOutputFile=gplot.pdf gplot.eps ; fi
> ../../run-octave -f -q -H -p . --eval "sparseimages ('grid', 'eps');"
> error: number of rows must match (79 != 1) near line 937, column 23
> error: called from:
> error:   /Users/bpabbott/Development/mercurial/octave-3.1.51/scripts/
> plot/__go_draw_axes__.m at line 937, column 6
> error:   /Users/bpabbott/Development/mercurial/octave-3.1.51/scripts/
> plot/__go_draw_figure__.m at line 59, column 8
> error:   /Users/bpabbott/Development/mercurial/octave-3.1.51/scripts/
> plot/gnuplot_drawnow.m at line 55, column 7
> error:   /Users/bpabbott/Development/mercurial/octave-3.1.51/scripts/
> plot/print.m at line 447, column 7
> error:   /Users/bpabbott/Development/mercurial/octave-3.1.51/doc/
> interpreter/sparseimages.m at line 231, column 5
> error:   /Users/bpabbott/Development/mercurial/octave-3.1.51/doc/
> interpreter/sparseimages.m at line 33, column 2
>
> make[3]: *** [grid.eps] Error 1
> make[2]: *** [interpreter] Error 2
> make[1]: *** [doc] Error 2
> make: *** [all] Error 2
>
> The offending line in __go_draw_axes__.m is
>
>        kids = [obj.children, kids];
>
> Which with John's change from row to column vector for handles needs
> to be
>
>        kids = [obj.children; kids];
>
> However, in this instance an empty vector with size [1, 0] fails.
>
> I replaced the line with
>
>          if (isempty (kids))
>            kids = obj.children;
>          elseif (! isempty (obj.children))
>            kids = [obj.children; kids];
>          endif
>
> and "make" and "make check" completed without further problems.
>
> I could offer a changeset to resolve the problem with
> __go_draw_axes__, but expect the the proper solution would to fix the
> concatenation of column vectors.
>
> Might someone with c++ skill take care of this, or if there are
> substantial problem with that, say the word and I'll submit a
> changeset for __go_draw_axes__.
>
> Ben
>
> Ben
>
>
>
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>

Ben,

I've just tried in Matlab 2007a:
 [ones(2,0);zeros(5,1)]

Matlab gives zeros(5,1), yet along with this warning:

Warning: Concatenation involves an empty array with an incorrect
number of columns. This may not be allowed in a future release.

Why ones(1,0) does not gripe, I don't know. I guess it's a bug in Matlab.
Anyway, I think that in light of this fact it doesn't seem reasonable
to bother with getting Matlab compatible here. And even if we do, I
think that code relying on such a behaviour is a bad idea.

regards

-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz