[scilab-Users] Solving multi-variable function

Fri Mar 14 09:53:06 CET 2008

Sorry for the misunderstanding.

To use fsolve, you need to have as many relations as variables, which is not
the case with your test.

If you have less equations than variables, but your problem has one solution
and only one (which is neither the case for your function test_fsolve),
then use optim with the square of your initial function.

Éric.

PS: by the way the error message is not as speaking as it should be...

2008/3/14, Jerry Wang <jerrwang at yahoo.com>:
>
>  Thanks Eric,
>
>
>
> But what do you mean defining x0 inside vs outside?  The func_for_fsolve
> function is declaired as
>
>       function [y] = func_for_fsolve ( x0 )
> and the caller provides the x0 as an vector into it...
>
>       [x_result,v,info]=fsolve([ret_age, mu_tree, delta_t,
> sigma_b],func_for_fsolve);
>
>
>
> Should be okay right?
>
>
>
> Also, are you able to run the simplified test_fsolve.sci and
> test_fsolve_caller.sce?  Do they work for you?  Or are you also getting
> error 98?
> http://www.imagingspot.com/scilab/test_fsolve.sci.txt
> http://www.imagingspot.com/scilab/test_fsolve_caller.sce.txt
>
>
>
> Jerry
>
>
> ----- Original Message ----
> From: Eric Dubois <grocer.toolbox at gmail.com>
> To: users at lists.scilab.org
> Sent: Thursday, March 13, 2008 2:16:49 PM
> Subject: Re: [scilab-Users] Solving multi-variable function
>
> I cannot run your function because you do not provide the function
> ABSPredictor. But, if your function func_for_fsolve.sci is exactly what is
> on your website, there are some oddities. In particular, you should not
> define x0 inside the function to maximise, but outside.
>
> Eric.
>
> 2008/3/13, Jerry Wang <jerrwang at yahoo.com>:
> >
> >  Oh, sorry, somehow the website doesn't like the .sci extension.  Please
> > see it here:
> >
> > *http://www.imagingspot.com/scilab/func_for_fsolve.txt*<http://www.imagingspot.com/scilab/>
> >
> > Yes, I provided initial values to the 4 variables.  The "caller"
> > function has:
> >
> > chdir('C:\MyScilab');
> > getf('ABSPredictor.sci')
> > getf('func_for_fsolve.sci');
> > tic();
> > ret_age=60;
> > mu_tree=36000;
> > delta_t=0.85;
> > sigma_b=0.50;
> > [x_result,v,info]=fsolve([ret_age, mu_tree, delta_t,
> > sigma_b],func_for_fsolve);
> > time_length=toc()
> > beep();
> >
> >
> > When debugging, the func_for_fsolve does fine for the first iteration.
> > Then it gives that error at the end of the first iteration.
> >
> > Jerry
> >
> >
> > ----- Original Message ----
> > From: Eric Dubois <grocer.toolbox at gmail.com>
> > To: users at lists.scilab.org
> > Sent: Thursday, March 13, 2008 12:46:42 PM
> > Subject: Re: [scilab-Users] Solving multi-variable function
> >
> > Unfortunately, the function is not available at the provided address...
> >
> > Did you provide values to ret_age, mu_tree, delta_t, sigma_b, in order
> > to  feed the optimization program?
> >
> > Eric.
> >
> >
> > 2008/3/13, Jerry Wang <jerrwang at yahoo.com>:
> > >
> > >  I did attempt to collapse the 4 variables into a single vector array
> > > but I received an error after fsolve reaches the end of the first
> > > iteration.  The error is:
> > >
> > > !--error 98
> > >  variable returned by scilab argument function is incorrect
> > >
> > >  --------------------------------------
> > > I add the function into the scope via:
> > > --------------------------------------
> > >     getf('func_for_fsolve.sci');
> > >
> > >  --------------------------------------
> > > I call the function via:
> > >  --------------------------------------
> > >     [x_result,v,info]=fsolve([ret_age, mu_tree, delta_t,
> > > sigma_b],func_for_fsolve);
> > >
> > >  --------------------------------------
> > > Inside func_for_solve I have:
> > >  --------------------------------------
> > > function [y] = func_for_fsolve ( x0 )
> > > ...
> > > ret_age = round(x0(1));
> > > mu_tree = x0(2);
> > > delta_t = x0(3);
> > > sigma_b = x0(4);
> > > ...
> > > [statistical_sustainable] =
> > > ABSPredictor(mc,now_age,ret_age,mu_tree,delta_t,sigma_b);
> > > ...
> > > y = abs(statistical_sustainable(index)./100 - 0.90);
> > > ...
> > > y = y + penalties;
> > > disp('testing123');
> > > disp('testing234');
> > > endfunction
> > >
> > > --------------------------------------
> > > --------------------------------------
> > >
> > > I tried testing the code by reducing the supplied argument x0 into 1
> > > scalar variable instead of the 4 scalar vector, and the function call
> > > worked.  That's why I went ahead and assumed that fsolve takes only one
> > > variables.  Can you see what I am doing wrong that's causing me to receive:
> > >  !--error 98
> > >  variable returned by scilab argument function is incorrect
> > >
> > >
> > > Thank you!
> > >
> > > Jerry
> > >
> > > ps. the complete func_for_fsolve.sci is uploaded here for your
> > > viewing:
> > > http://www.imagingspot.com/scilab/func_for_fsolve.sci
> > >
> > >
> > >
> > >
> > > ----- Original Message ----
> > > From: Eric Dubois <grocer.toolbox at gmail.com>
> > > To: users at lists.scilab.org
> > > Sent: Thursday, March 13, 2008 5:41:21 AM
> > > Subject: Re: [scilab-Users] Solving multi-variable function
> > >
> > > Fsolve takes one variable input, but the input can be a vector of any
> > > size.
> > >
> > > So, collapse your 4 variables into a single vector and adapt your
> > > fonction accordingly.
> > >
> > > Eric.
> > >
> > >
> > > 2008/3/13, Jerry Wang <jerrwang at yahoo.com>:
> > > >
> > > >  Hello Scilab-ers,
> > > >
> > > > Can any one point me to the right direction?  I want to find the
> > > > zero point of a function that has 4 variables.  I want scilab to solve for
> > > > the values of the 4 variables that would give me a result = 0 for the
> > > > answer.  I initially tried fsolve, but I discovered that fsolve only take
> > > > one variable input.
> > > >
> > > > Any thoughts?  Thanks!
> > > >
> > > > Jerry
> > > >
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> > > >
> > >
> > >
> > >
> > >
> > >
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> > >
> >
> >
> >
> >
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> >
>
>
>
>
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