Analysis by SBC

392

Name	문정웅

Subject	gauss_el

% gauss_el.m
% Programmed by 문정웅

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 =

  6.3632e-015

ans =

   -7.2008
    3.4116
    5.7833
   -1.6668
    2.8751
   -0.2326
   -2.5189
    3.5883
    1.6561
   -1.0576

>>

DATE: 2013.10.10 - 15:08

gauss_el