# plot command is not work in Gauss Seidel Method

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suketu vaidya on 4 Dec 2020
Answered: suketu vaidya on 4 Dec 2020
A = [
1 0 -1 0 0 0 0
-1 1 1 0 0 0 0
0 -1 2 -1 0 0 0
0 -1 0 2 0 1 0
0 -1 -1 0 2 1 1
0 0 1 -1 0 2 -1
0 0 0 -1 1 -1 2
];
b = [0 0 0 0 0 20 0]';
x=[1 1 1 1 1 1 1];
n=size(x,1);
normVal=Inf;
tol=1e-5; itr=0;
%%Gauss Seidel Method
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('system solution : \n%f\n%f\n%f\n%f in %d iterations',x,itr);
hold on
plot(itr,x, '+')
xlim([0 10])
ylim([0 2])
hold off
end

John D'Errico on 4 Dec 2020
When you tell us that something does not work, you need ot explain why you THINK it does not work. In fact, plot worked perfectly well there. At least, it tiried to work as well as it could.
itr
itr =
2
x
x =
0 1 1 1 1 1 1
plot(itr,x, '+')
So itr is the number 2. x is a vector. What did you expect it to do?
##### 2 CommentsShowHide 1 older comment
suketu vaidya on 4 Dec 2020
easy way i try to plot ans of gauss seidel method

### More Answers (1)

suketu vaidya on 4 Dec 2020
right ans is
hold on
plot(x,'o')