```Date: Dec 1, 2012 1:12 PM
Author: Joshua
Subject: Problem solving nonlinear equations with matrices

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 usingd=K\Fwhere 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 solved=K\Fbecause it gives me the trivial zero solution.  I have to insert an equation based on a diagonal matrix M such thatM_i*d(i)^2=1  (sum on i from 1 to the size of the K matrix)or M11*d1^2 + M22*d2^2 + ... + Mnn*dn^2 = 1where n is the number of rows/columns in K.My procedure is to remove one equation (or row) from the K matrix, leaving n-1 equations, and to solve these equations with the M_i*d(i)^2=1 equation to give me a nonzero d solution.  My problem is...how?  I am new to MATLAB and have no clue how to do this.  I've tried using fsolve but keep getting various error messages.  Help?!
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