From bug-octave-request at bevo dot che dot wisc dot edu  Wed Oct 21 14:48:24 1998
Subject: Problem with fsolve
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Daniel Tourde <ted at ffa dot se>
Cc: help-octave at bevo dot che dot wisc dot edu, bug-octave@bevo.che.wisc.edu,         jwe@bevo.che.wisc.edu
Date: Wed, 21 Oct 1998 14:47:46 -0500 (CDT)

On 21-Oct-1998, Daniel Tourde <ted at ffa dot se> wrote:

| I'm trying to use fsolve and I have a lot of troubles.
| 
| If I consider the following function :
| 
| function y = test2(x)
| 
|   y(1) = x(1)*x(2)-2;
|   y(2) = x(2)^2 -4;
|   y(3) = x(1)^2 -1;
|   y(4) = x(1) + x(2) -3;
| 
| endfunction 
| 
| where quite obviously the solutions are 1 and 2 if the forth condition
| is taken into account, I obtain :
| 
| 1 and 2 if I type [y,index] = fsolve[test2,[10,10])
| index = 1
| 
| but also the wrong solution 
| 
| -1 and -2 if I type [y,index] = fsolve[test2,[-10,-10])
| index = 1
| 
| Where is the problem ? 
| 
| Why the y(4) specification is not taken into account ?

I think the problem is that fsolve expects a square system of
equations (number of variables == number of equations).

BTW, there is no need to send a message to me as well as the help- or
bug-octave mailing lists.  I read both.

Thanks,

jwe