The formula doesn't calculate

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I am calculating a matrix using Gaussian elimination, but the calculation does not work under the following conditions.
A=[2 0 1; -2 4 1; -1 -1 3] b=[8 ; 0 ;2 ] x=[x1; x2; x3]
I think it doesn't work because there is a 0 in row 1 and column 2 of A. How should I change the code? Have a nice day everyone:)
here is a code
clc; clear all; close all;
A = [2 0 1 ; -2 4 1 ;-1 -1 3];
b = [8 0 2]';
%b = [7; 8 ;3];
sz = size(A,1);
disp ([A b]);
for i = 2 :1: sz
for j = 1:1:i-1
k = A(j,j)/A(i,j);
A(i,:) = k * A(i,:) - A(j,:);
b(i) = k * b(i) - b(j);
disp([A b]);
end
end
for i = sz-1:-1:1
for j = sz:-1:i+1
k = A(j,j)/A(i,j);
A(i,:) = k*A(i,:)-A(j,:);
b(i) = k* b(i) - b(j);
disp([A b]);
end
end
x = b./diag(A);
disp([A b]./diag(A));
disp(x);

采纳的回答

Pooja Kumari
Pooja Kumari 2024-4-12
编辑:Pooja Kumari 2024-4-12
Hello,
The issue with your code is not because there is a 0 in row 1 and column 2 of A. Key corrections in your code is as follows:
  1. Forward Elimination Corrected: Properly calculates the factor (k) for each element to be eliminated, ensuring correct elimination of elements below the pivot.
  2. Back Substitution Implemented: Solves for variables from the bottom up after converting (A) to an upper triangular form, ensuring accurate calculation of solution vector (x).
clc; clear all; close all;
A = [2 0 1 ; -2 4 1 ;-1 -1 3];
b = [8; 0; 2];
sz = size(A,1);
disp ([A b]);
% Forward elimination
for i = 1:sz-1
for j = i+1:sz
k = A(j,i)/A(i,i);
A(j,:) = A(j,:) - k * A(i,:);
b(j) = b(j) - k * b(i);
end
end
% Back substitution
x = zeros(sz,1); % Initialize solution vector
for i = sz:-1:1
x(i) = (b(i) - A(i,i+1:sz)*x(i+1:sz))/A(i,i);
end
disp(x);
  1 个评论
재훈
재훈 2024-4-12
wow... you are genius to me. thx for yor help and have a good day. I really appreciate of you. cheerio!

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