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Topic: Problem solving nonlinear equations with matrices
Replies: 4   Last Post: Dec 3, 2012 2:58 PM

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 Steven Lord Posts: 18,038 Registered: 12/7/04
Re: Problem solving nonlinear equations with matrices
Posted: Dec 2, 2012 11:08 PM

"Joshua " <Hogy88@aol.com> wrote in message
news:k9dh9o\$mn6\$1@newscl01ah.mathworks.com...
> Hello,
>
> I am working with the Finite Element Method using MATLAB and I have run
> into a technical problem. For the basic finite element procedure, a
> stiffness matrix K and a force vector F are created, and the results we
> want to find are solved using
>
> d=K\F
>
> where K and F have no variables, only numbers. Now, however, I am doing a
> vibration problem and need some help to put a nonlinear equation into the
> matrix, or to solve it simultaneously.
>
> Here's my problem:
>
> I have a square matrix K of only numbers and my force vector F is zeros.
> I cannot just solve
>
> d=K\F
>
> because it gives me the trivial zero solution. I have to insert an
> equation based on a diagonal matrix M such that

Use the NULL function to determine a basis for the nullspace of K.

--
Steve Lord
slord@mathworks.com