From octave-maintainers-request at bevo dot che dot wisc dot edu  Fri Aug 18 11:32:56 2000
Subject: proper lvalues and whatnot
From: "Ross A. Lippert" <ripper at cs dot sandia dot gov>
To: "octave-maintainers at bevo dot che dot wisc dot edu"   <octave-maintainers@bevo.che.wisc.edu>
Date: Fri, 18 Aug 2000 10:29:34 -0600


One of the neat things about octave is its incorporation of
C-like syntax, with cool operators like ++ and += and so on.

I am wondering why it is not the case that assignment expressions
are not likewise lvalues?

Is there some reason why
octave> (v = zeros(1,2))++ 
should not give
 v = [1 1]
??

Also, I am wondering why it is that while subscripted vectors/matrices
are lvalues, that
octave> v = [1 1];
octave> v([1 1 2])++
does not give
 v = [3 2];
??

OK, so maybe I am a sick puppy.  But this is what I am really after.

> [i,j,nz] = find(M);
> (y=zeros(max(i),1))(i) += nz.*x(j)
and have
 y = M*x

I have a lot of sparse matrices I want to play with and this sort of
syntax would rock.


Is there a conceptual reason why I should not try to modify octave to
do this (i.e. how does this break the .m language as a language)?

Is there a technical reason why I should not try to modify octave to
do this (i.e. requires a total interpreter rewrite, I'd be in over my
head)?


-r