From bug-octave-request  Thu May 27 10:51:38 1993
Subject: I think this is a bug
From: esm (Edward Scott Meadows)
To: bug-octave
Date: Thu, 27 May 93 10:51:32 -0500

I'm having problems with a global parameter passed to the objective
function for npsol.

Here's the transcript of a bad octave session: 

--------------------Begin Bad-------------------------------------------

Octave, version 0.71.8.  Copyright (C) 1992, 1993, John W. Eaton.
This is free software with ABSOLUTELY NO WARRANTY.
For details, type `warranty'.

octave:1> x0=rand(2,1)
x0 =

  0.750686
  0.072777

octave:2> u=rand(3,1)
u =

  0.50838
  0.84761
  0.50798

octave:3> [u,obj,info]=npsol(u,'phi')
error: `x0' undefined

octave:3> x0
x0 =

  0.750686
  0.072777

octave:4> global x0
octave:5> [u,obj,info]=npsol(u,'phi')
error: index invalid or out of range for scalar type

octave:5> x0
x0 = 1

-------------End Bad-----------------------------------------------

Note that phi (included below) doesn't alter x0.  

Simply declaring x0 to be global after forgetting doesn't work.  npsol
will never work again the correct way unless I quit and restart
Octave.

Here's the transcript of a good octave session:

------------Begin Good--------------------------------------------

Octave, version 0.71.8.  Copyright (C) 1992, 1993, John W. Eaton.
This is free software with ABSOLUTELY NO WARRANTY.
For details, type `warranty'.

octave:1> x0=rand(2,1)
x0 =

  0.75062
  0.92573

octave:2> u=rand(3,1)
u =

  0.30012
  0.13089
  0.97077

octave:3> global x0
octave:4> [u,obj,info]=npsol(u,'phi')
u =

  -0.916283
   0.096027
   0.034535

obj = 2.3779

info = 0

octave:5> x0
x0 =

  0.75062
  0.92573

octave:6> 

---------End Bad--------------------------------------------------------

Here are f and phi, which are called from within npsol:

function out=phi(u);
out=u'*u+x0'*x0;
x=x0;
for i=1:max(size(u));x=f(x,u(i));out=out+x'*x;end;
return;
end;

function out=f(x,u);
out=0*ones(2,1);
out(1)=x(1)+u;
out(2)=x(2)+u**3;
return;
end;