[scilab-Users] Solving multi-variable function
Eric Dubois
grocer.toolbox at gmail.com
Fri Mar 14 20:11:51 CET 2008
I do not personnaly use fsolve, but you have examples in the help file (help
fsolve).
Eric
2008/3/14, Jerry Wang <jerrwang at yahoo.com>:
>
> Oh I see. I was using fsolve incorrectly. Thank you Eric.
>
>
>
> Can you or someone give me an example of fsolve solving two or more
> variables with two or more equations? This way I can use it correctly next
> time? Thank you.
>
>
>
> Jerry
>
>
> ----- Original Message ----
> From: Eric Dubois <grocer.toolbox at gmail.com>
> To: users at lists.scilab.org
> Sent: Friday, March 14, 2008 1:53:06 AM
> Subject: Re: [scilab-Users] Solving multi-variable function
>
> 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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