fsolve problem

[Rolf Fabian]

John W. Eaton wrote:
> 
> On 20-Feb-2008, Rolf Fabian wrote:
> 
> | 
> | For functions like e.g.
> |      F = "x(1).^19 + x(2).^19 - 1"
> | fsolve returns output x == input x0 as well as successful
> | iteration  flag (info =1) despite the fact that
> | fval(1) > 10^15 which is definitely far from zero.
> | 
> | BTW 
> | Why is 'fval' not a scalar ?
> 
> Because Octave's fsolve expects to be solving square systems.  It
> should detect this and fail.
> 
> jwe
> 
> 


Your answer confuses me a bit because e.g. the following example works
perfectly
as expected ( apart from the 'extra' output of fval and the transposition of
output x)
even though it is not 'square':

octave-3.0.0.exe:> [x,fval,info]  =  fsolve( F = "x(1).^5+x(2).^5 - 1",  x0=
rand(1,2) )
x =
   0.999989047698090
   0.140505453056555

fval =
   2.22044604925031e-016
   4.69821032358962e-294

info =  1

octave-3.0.0.exe:> x0
x0 =
   0.934687064878899   0.140505560616182

octave-3.0.0.exe:> eval(F)
ans = 2.22044604925031e-016

Rolf 

-----
Rolf Fabian
<r dot fabian at jacobs-university dot de>

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