Re: matrix of variables? <- thanks

[jdonner]

Jeff wrote:
> >  I'm trying to solve a non-linear equation with 25 vars,
> > and it works when I number them from x(1) .. x(25) but,
> > they naturally are a 2D array of variables, is there some way I can I 
> > use matrix notation for convenience?
> > When I try to say this:
> > function y = f (x)
> > g = 0.9;
> > # center parts
> > y(2,2) = -1 * x(2,2) + (1/4)*g*(x(1,2) + x(2,1) + x(2,3) + x(3,2));
> > y(2,3) = -1 * x(2,3) + (1/4)*g*(x(1,3) + x(2,2) + x(2,4) + x(3,3));
> > ... more
> >
> > I get:
> > error: invalid column index = 2
> > error: evaluating binary operator `*' near line 4, column 13
> > error: evaluating binary operator `+' near line 4, column 22
> > error: evaluating assignment expression near line 4, column 8
> > error: called from `f'
> > error: fsolve: evaluation of user-supplied function failed
> >
> > Is there a way to do this?

Heber Farnsworth wrote:
> Define x as a vector and then reshape it into a matrix within the function.
>
> x = reshape(x,5,5);

Thanks for that.  Also, zeros(5,5) works as far as declaring 
x and y as 2D.  I have to reshape at the end (I think) but at least 
octave is not complaining. 
Thanks again, 

Jeff



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