Partial pivoting problem in matrix

4 ビュー (過去 30 日間)
Netanel Malihi
Netanel Malihi 2021 年 12 月 4 日
回答済み: Pranjal Kaura 2021 年 12 月 30 日
I'm getting a mistake in my matrix when trying to get the max number at the column and swiching rows , I'm pretty sure its got to do with an incorrect index.
Im using the partial pivoting method.
thank you for your help.
clear;
clc;
n=5;
v=repelem(4,n);
A=diag(v);
i=1;
j=1;
A(1,n)=-1
A(n,1)=-1
for i=1:n
for j=1:n
if i==j+1 ||j==i+1
A(i,j)=-1;
end
end
end
b=1:n;
B=b'/n;
A=[A,B]
for k=1:n-1
[max_A1,row_i]=max(abs(A(k:end,k)))
if row_i~=k
A1=A(k,:)
A(k,:)=A(k,:)
A(row_i,:)=A1
else
end
for i=k+1:n
L=A(i,k)/A(k,k)
for j=k:n+1
A(i,j)=A(i,j)-L*A(k,j)
end
end
end

採用された回答

Pranjal Kaura
Pranjal Kaura 2021 年 12 月 30 日
Hey,
Please refer the code below
clear;
clc;
n=5;
v=repelem(4,n);
A=diag(v);
i=1;
j=1;
A(1,n)=-1;
A(n,1)=-1;
for i=1:n
for j=1:n
if i==j+1 ||j==i+1
A(i,j)=-1;
end
end
end
b=1:n;
B=b'/n;
A=[A,B];
% test matrices
% A = [25 5 1 106.8;
% 64 8 1 177.2;
% 144 12 1 279.2];
% A = [1 2 -4 3;
% 2 5 -6 10;
% -2 -7 3 -21;
% 2 8 -5 38];
% n = 4;
%partial pivoting code
for k=1:n-1
[max_A1,row_i]=max(abs(A(k:end,k)));
row_i = row_i - 1 + k;
if row_i~=k
A1=A(k,:);
A(k,:)=A(row_i,:);
A(row_i,:) = A1;
end
for i=k+1:n
L=A(i,k)/A(k,k);
A(i, k:end) = A(i, k:end) - A(k, k:end)*L;
% for j=k:n+1
% A(i,j)=A(i,j)-L*A(k,j)
% end
end
end
Hope this helps!

その他の回答 (0 件)

カテゴリ

Help Center および File ExchangeDates and Time についてさらに検索

タグ

製品


リリース

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by