How do i reduce running time in this code
2 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
function [f , t] = jacobi2(n)
tic;
if n < 4
error ('n not in the range')
end
n=n^2;
b=zeros(n,1);
b(1,1)=1;
b(n,1)=1;
A = zeros(n,n);
for i=4:(n-3)
for j=4:(n-3)
if i==j
A(i,i)=4;
A(i,i+1)=-1;
A(i,i-1)=-1;
A(i,i+3)=-1;
A(i,i-3)=-1;
A(i+1,i)=-1;
A(i-1,i)=-1;
A(i+3,i)=-1;
A(i-3,i)=-1;
end
end
end
A(1,1)=4;
A(1,2)=-1;
A(3,2)=-1;
A(2,3)=-1;
A(2,1)=-1;
A(2,2)=4;
A(3,3)=4;
A(end,end)=4;
A(end-1,end-1)=4;
A(end-2,end-2)=4;
A(end-3,end-3)=4;
A(end-1,end)=-1;
A(end,end-1)=-1;
A(end-1,end-2)=-1;
A(end-2,end-1)=-1;
epsilon = 1e-3;
f = zeros(n,1);
counter = 0;
flag = 0;
L = tril(A,-1);
D = diag(A);
U = triu(A,1);
B = -1./D.*(L+U);
C = (1./D).*b;
while flag == 0
counter = counter+1;
if counter > 10000
error ('Too many iteration')
end
f_n = (B*f) + C;
if max(abs(f_n-f)/(f_n))<epsilon
flag = 1;
else
f = f_n;
end
end
t=toc;
end
0 Kommentare
Antworten (1)
Swetha Polemoni
am 20 Dez. 2020
Hi Tzach Berlinsky,
In the code you have provided using nested loops is not necessary. Since the body of loops is executed only when i==j, elimination of one loop can be an option. Replace the nested loops with the following.
for i=4:(n-3)
A(i,i)=4;
A(i,i+1)=-1;
A(i,i-1)=-1;
A(i,i+3)=-1;
A(i,i-3)=-1;
A(i+1,i)=-1;
A(i-1,i)=-1;
A(i+3,i)=-1;
A(i-3,i)=-1;
end
Here is the link to best practices that can be followed to improve performance. You may find it helpful.
0 Kommentare
Siehe auch
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!