Analysis by SBC

392

Name	박가영

Subject	gauss_el

% gauss_el.m
% Gauss Elimination to solve A*x = b
% input : A, b
% output : x
% Programmed by Park, Ga-Young

function x = gauss_el(A,b);
A = myrand(8,8,1,9); b = myrand(8,1,1,5);
n = length(A);
R = [A b];

for j=1:n-1
    for i=j+1:n
        if R(j,j)==0
            max_id = find( max( abs(R(j+1:n,j)) ) ) + j; % Find pivot
            temp = R(j,:);  % Change two rows
            R(j,:) = R(max_id,:);  R(max_id,:) = temp;
        end
        a = R(i,j)/R(j,j);
        R(i,:) = R(i,:) - a*R(j,:);
    end
end
% 역대입법
A = R(:,1:n); b = R(:,n+1);
x = zeros(n,1);
for j=n:-1:1
    x(j) = ( b(j) - A(j,j+1:n)*x(j+1:n) )/A(j,j);
end
norm( b-A*x )

%%%%%%%

>> A=myrand(10,10,1,10); b=myrand(10,1,10,20);
>> x=gauss_el(A,b)

ans =

   8.9729e-15

x =

   -2.0315
    3.6155
   -2.4647
    3.0537
   -1.0681
   -0.1045
    0.4973
   -1.5422

DATE: 2013.10.10 - 14:55

gauss_el

gause_el