Gauss-Seidel iterative method with no relaxation factor

Hi I want to create a Matlab code for Gauss-Seidel iterative method with no relaxation factor and use the solution using a termination tolerance=.01% for the relative approximate error. This is what I got so far. For some reason my stigma is zero and it won't able to calculate it

A= [60 -40 0; -40 60 -20; 0 -20 20]

b=[29.4; 39.2; 58.8]

x=[0 0 0 0]'

n=size(x,1);

normVal=Inf;

%%

% * _*Tolerence for method*_

tol=1e-5; itr=0;

%%

while normVal>tol

x_old=x;

for i=1:n

sigma=0;

for j=1:i-1

sigma=sigma+A(i,j)*x(j);

end

for j=i+1:n

sigma=sigma+A(i,j)*x_old(j);

end

x(i)=(1/A(i,i))*(b(i)-sigma);

end

itr=itr+1;

normVal=norm(x_old-x);

end

%%

fprintf('Solution of the system is : \n%f\n%f\n%f\n%f in %d iterations',x,itr);

Answer 1

[Sreeranj Jayadevan]

I have executed the given code in MATLAB and it is giving me the required output. It seems to me that you have accidentally initialized the solution vector "x" as a 4 by 1 array. Since only three equations are involved in the problem, "x" should be a 3 by 1 array i.e

x=[0 0 0]';

[Dai Nguyen]

Thank you