[scilab-Users] Solving multi-variable function

[Jerry Wang]

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
 
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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