I have a question relate to Gauss seidel method

Implement the Gauss-Seidel method for solving a system of linear equations from scratch in MATLAB and walk me through your thought process in constructing the code. Additionally, demonstrate that your implementation works by applying it to the following system. 2x +3y −z =7 , x −2y+4z =1 , 3x +y+2z =8

%Gauss seidel
A=input('Enter a co-efficient matrix A: ');
B=input('Enter source vector B: ');
P=input('Enter initial guess vector: ');
n=input('Enter number of iterations: ');
e=input('Enter tolerance: ');
N=length(B);
X=zeros(N,1);
Y=zeros(N,1); %for stopping criteria
for j=1:n
    for i=1:N
        x(i)=(B(i)/A(i,i))-(A(i,[1:i-1,i+1:N])*P([1:i-1,i+1:N]))/A(i,i);
        P(i)=X(i);
    end
    fprintf('Iterations no %d \ n' ,j)
    X
    if abs (Y-X)<e
        break
    end
    Y=X;
end

This is my code is this correct? please help me

[Torsten]

Adapt the inputs (A,B,P,n,e) to your actual problem so that we can run the code.

You won't get convergence with Gauss-Seidel:

D = diag([2,-2,2]);
U = [0,3,-1;0,0,4;0,0,0];
L = [0,0,0;1,0,0;3,1,0];
M = -inv(L+D)*U;
norm(M,2)

ans = 4.0790

[Kumuthu]

Thank you i'll try

Answer 1

[John D'Errico]

Updating the vector x (small x) and then looking to see if the vector X (capital X) is converging seems like a bad idea. You did this:

x(i)=(B(i)/A(i,i))-(A(i,[1:i-1,i+1:N])*P([1:i-1,i+1:N]))/A(i,i);

But you never use the vector x again. Instead all comparisons are done with X.

Yes, I suppose one day, after running for so many years, your computer may be so old it does not recognize the difference. Maybe then it might do something. Who knows? ;-)

Case matters in MATLAB.

[Kumuthu]

Thank you i'll try