Analysis by SBC

392

Name	선민주

Subject	gauss_el.m

% gauss_el.m
% Programmed by 선민주

function x = gauss_el(A,b);
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
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(8,8,1,10); b = myrand(8,1,10,20)

b =

    17
    13
    14
    19
    17
    12
    18
    16

>> x = gauss_el(A,b)

ans =

  1.9860e-015

x =

    1.8490
    0.2148
   -0.4661
    1.3613
   -0.0846
   -0.0117
    0.8911
   -1.3097

>>

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

>> gauss_el(A,b)

ans =

  4.0229e-015

ans =

    3.5157
   -0.3088
    1.7578
   -1.2104
    0.8081
   -1.4135
   -0.1175
   -1.1693

DATE: 2013.10.10 - 15:22

LAST UPDATE: 2013.10.10 - 15:27

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