Jacobi method in Matlab
2 次查看(过去 30 天)
显示 更早的评论
My jacobi method not working. I feel like I'm missing something. Currently my numbers that are result back are m = 1 and be = 1.6. I wonder if I'm breaking out of one of the loops to fast
How to run :
n=100
[a,b]=sparsesetup(100);
[m,be] = Jacobi(a,b,0.00000025)
should result with -- getting wrong values
m = 36
be = 4.5785 * 10^-7
function [m,be] = Jacobi(a,b,tol)
n = length(b)
d= diag(a); % extract diagonal of a[i,j]
r=a-diag(d);
x=zeros(n,1);
p=zeros(n,1)
c=zeros([n,1]);
e=zeros([n,1]);
n1 =0;
err =0;
relerr = 1;
while(1)
x=b(b-r*x) ./d;
err =abs(norm(x-p));
relerr = err/(norm(x) + eps);
p=x;
n1= n1+1
if(err)
break
end
end
xc=x;
m=n1;
for i=1 : n
for j=1 : n
xa(j) = 1;
c(i) = c(i) + a(i,j) * xa(j);
e(i) = e(i) + a(i,j) * xc(j);
end
end
for i =1 : n
dif(i) = abs(xa(i) - xc(i));
dif2(i) = abs(e(i) - c(i));
end
fe = max (dif, [], 2);
be = max(dif2, [],2);
end
// sparesetup method
function [a,b] = sparsesetup (n)
e = ones(n,1);
a= spdiags ([-e 3*e -e], -1:1, n,n); %Entries of a{i,j}
b = zeros (n,1); % Entries of rhs b
b(1) = 2;
b(n) = 2;
b(2:n-1)=1;
end
3 个评论
Walter Roberson
2021-2-27
x=b(b-r*x) ./d;
That is indexing. Is it possible that you want multiplication instead of indexing?
回答(0 个)
另请参阅
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!