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From: Abhishek on 14 Jul 2010 10:33
hi
i am working on a circuit for which i have written 13 equations in 13 variables to calculate the transfer function in terms of ckt parameters (using kirchoffs);
But my equations include a lot of ckt parameters which i have to substitute later.
I am using syms function to declare those parameters but my parameters are exceeding 52 so i have to use a1 ,a2,etc ;;;
when i run to calculate the transfer fuction matlab does not respond for long time ......
can u please give me a reason and answer to this problem please??
please help me ....
From: Steven Lord on 14 Jul 2010 12:54

"Abhishek " <abhi14jan(a)yahoo.com> wrote in message
news:i1khr4$l3s$1(a)fred.mathworks.com...
> hi
> i am working on a circuit for which i have written 13 equations in 13
> variables to calculate the transfer function in terms of ckt parameters
> (using kirchoffs);
> But my equations include a lot of ckt parameters which i have to
> substitute later.

So you actually have 13 equations in many more than 13 unknowns.

> I am using syms function to declare those parameters but my parameters are
> exceeding 52 so i have to use a1 ,a2,etc ;;;
> when i run to calculate the transfer fuction matlab does not respond for
> long time ......
> can u please give me a reason and answer to this problem please??

The more complicated the expression and the more unknown quantities it
includes, the more work the solver will have to do to try to solve it. If
you have parameters whose values you know ahead of time, substitute them
into the expressions BEFORE attempting to solve them. It may seem like that
will require more work (if you have multiple parameter values to test) but
solving more systems (that are easier to solve) may be quicker than solving
one system (that's very difficult to solve.)

--
Steve Lord
slord(a)mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ
To contact Technical Support use the Contact Us link on
http://www.mathworks.com


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