Re: Problem defining global vars

[Stefan van der Walt]

Hi Christian

The variables 'a' and 'b' are outside the scope of function xdot, so
you need to explicitly define them to be global:

function xdot = f(x,t)
  global a;
  global b;
  xdot = a*x + b;
endfunction

Regards
Stefan

On Mon, Jun 28, 2004 at 05:03:31PM -0500, Christian Renz wrote:
> When I run the following script, octave complains that a and b are 
> undefined. Once I move the definitions inside the function f, 
> everything works fine, however. Is there a way I can define a and b so 
> they are recognized by f (when used via lsode)?
> 
> ----------8<----------8<----------
> global a = [ -1, 0.5 ; 1, -1];
> global b = [ 0.5 ; 0.5 ];
> 
> function xdot = f(x, t)
>     xdot = a*x + b;
> endfunction
> 
> x0 = [ 5; 0 ];
> t = linspace(0, 10, 100)';
> x = lsode("f", x0, t);
> 
> plot (t, x);
> ----------8<----------8<----------



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