# Homework Help: MATLAB Gaussian Elimination

1. Sep 23, 2013

### thekkid33

1. The problem statement, all variables and given/known data
I am writing a GE program and i think i have that correct. I have a matrix and i am trying to find the correct answer. I am not sure where i am going wrong.

2. Relevant equations

3. The attempt at a solution

%GE with no pivoting
function x=ge_nopivot(A,b)
n=length(A); Ab=[A b];
for k=1 : n-1
for i=k+1 : n
ratio=Ab(i,k)/Ab(k,k);
Ab(i,k : n+1)= Ab(i,k : n+1)-ratio*Ab(k,k : n+1);
end
end
%back subsitution
x=zeros(n,1); x(n)=Ab(n,n+1)/Ab(n,n);
for i=n-1 : -1 : 1
x(i)=(Ab(i,n+1)-Ab(i,i+1:n)*x(i+1 : n))/Ab(i,i);
end

A=[-cosd(30) 0 cosd(60) 0 0 0; -sind(30) 0 -sind(60) 0 0 0; cosd(30) 1 0 1 0 0; sind(30) 0 0 0 1 0; 0 1 cosd(60) 0 0 0; 0 0 sind(60) 0 0 1]; b=[0;2000;0;0;0;0];
>> n=length(A)

n =

6

>> Ab=[A b]

Ab =

1.0e+03 *

-0.0009 0 0.0005 0 0 0 0
-0.0005 0 -0.0009 0 0 0 2.0000
0.0009 0.0010 0 0.0010 0 0 0
0.0005 0 0 0 0.0010 0 0
0 0.0010 0.0005 0 0 0 0
0 0 0.0009 0 0 0.0010 0

>> x=ge_nopivot(A,b)