Thread Subject: solve system of nonlinear equations in simulink

Hello everyone,

I am trying to solve a system of nonlinear algebraic equations in simulink. The reason I want to solve equations in simulink (and not MATLAB) is that the input parameters of the objective function are varying with time and a new set of equationa must be solved at each time step.
It appears to me that simulink cannot support fsolve() functions and alike. Can anyone let me know how to construct such a model please?

Thanks very much,
Masih

On 1/18/2012 11:49 PM, Masih Mahmoodi wrote:
> Hello everyone,
>
> I am trying to solve a system of nonlinear algebraic equations in simulink.
>The reason I want to solve equations in simulink (and not MATLAB) is that the
>input parameters of the objective function are varying with time and a new set
>of equationa must be solved at each time step.

Hello;

So, why can't the above be done in Matlab? can't you generate new set of equations
at each time step in Matlab? Why not?

> It appears to me that simulink cannot support fsolve() functions and alike.
>Can anyone let me know how to construct such a model please?
>
> Thanks very much,
> Masih

Yes, I was thinking if I could solve the equations from MATLAB at each time step and send it to simulink and vice versa, but I don't know how to do this. Could you please let me know how I can set up the code structure?

Thanks very much,
Masih

"Nasser M. Abbasi" <nma@12000.org> wrote in message <jf8b4d$90k$1@speranza.aioe.org>...
> On 1/18/2012 11:49 PM, Masih Mahmoodi wrote:
> > Hello everyone,
> >
> > I am trying to solve a system of nonlinear algebraic equations in simulink.
> >The reason I want to solve equations in simulink (and not MATLAB) is that the
> >input parameters of the objective function are varying with time and a new set
> >of equationa must be solved at each time step.
>
> Hello;
>
> So, why can't the above be done in Matlab? can't you generate new set of equations
> at each time step in Matlab? Why not?
>
> > It appears to me that simulink cannot support fsolve() functions and alike.
> >Can anyone let me know how to construct such a model please?
> >
> > Thanks very much,
> > Masih
>

On 1/19/2012 12:27 AM, Masih Mahmoodi wrote:
> Yes, I was thinking if I could solve the equations from MATLAB at each time step and send it
>to simulink and vice versa, but I don't know how to do this. Could you please
>let me know how I can set up the code structure?
>

not my area, but may be this helps:

http://www.mathworks.com/help/toolbox/simulink/slref/toworkspace.html

"To Workspace - Write data to MATLAB workspace"

good luck with your project

--Nasser

"Masih Mahmoodi" <masih.mahmoodi10@gmail.com> wrote in message
news:jf8asm$jli$1@newscl01ah.mathworks.com...
> Hello everyone,
>
> I am trying to solve a system of nonlinear algebraic equations in
> simulink. The reason I want to solve equations in simulink (and not
> MATLAB) is that the input parameters of the objective function are varying
> with time and a new set of equationa must be solved at each time step. It
> appears to me that simulink cannot support fsolve() functions and alike.
> Can anyone let me know how to construct such a model please?

Use the Algebraic Constraint block, perhaps?

http://www.mathworks.com/help/toolbox/simulink/slref/algebraicconstraint.html

I'm not sure if it can solve multiple equations simultaneously (passed in as
a bus?) If it can't, and you are not looking to generate code from the
system, then I think the User-Defined Functions blocks may help you.

http://www.mathworks.com/help/toolbox/simulink/slref/f4-4889.html#f4-5797

--
Steve Lord
slord@mathworks.com
To contact Technical Support use the Contact Us link on
http://www.mathworks.com

"Steven_Lord" <slord@mathworks.com> wrote in message <jf9a78$o0s$1@newscl01ah.mathworks.com>...
>
>
> "Masih Mahmoodi" <masih.mahmoodi10@gmail.com> wrote in message
> news:jf8asm$jli$1@newscl01ah.mathworks.com...
> > Hello everyone,
> >
> > I am trying to solve a system of nonlinear algebraic equations in
> > simulink. The reason I want to solve equations in simulink (and not
> > MATLAB) is that the input parameters of the objective function are varying
> > with time and a new set of equationa must be solved at each time step. It
> > appears to me that simulink cannot support fsolve() functions and alike.
> > Can anyone let me know how to construct such a model please?
>
> Use the Algebraic Constraint block, perhaps?
>
> http://www.mathworks.com/help/toolbox/simulink/slref/algebraicconstraint.html
>
> I'm not sure if it can solve multiple equations simultaneously (passed in as
> a bus?) If it can't, and you are not looking to generate code from the
> system, then I think the User-Defined Functions blocks may help you.
>
> http://www.mathworks.com/help/toolbox/simulink/slref/f4-4889.html#f4-5797
>
> --
> Steve Lord
> slord@mathworks.com
> To contact Technical Support use the Contact Us link on
> http://www.mathworks.com

doesn't matlab function block work in this case?

Pietro