33 lines
656 B
Mathematica
33 lines
656 B
Mathematica
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# upper matrix.
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clear,clc
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#U2 = -A(2,1)/A(1,1) * A(1, :) + A(2, :)
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#U3 = -A(3,1)/A(1,1) * A(1, :) + A(3, :)
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#U = [A(1,:); U2; U3]
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#U3 = -A(3,2)/U(2,2) * U(2, :) + U(3, :)
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#U = [A(1,:); U2; U3]
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#L = [1, 0, 0; A(2,1)/A(1,1),1,0;(A(3,1)/A(1,1)),(A(3,2)/U(2,2)),1]
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# U var = A (matrix)
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# for i < n
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# j = i + 1
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# for j <= n
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# U(j, :) = -U(j,i)/U(j,i) * U(i, :) + U(j, :)
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A = [5,2,4;2,1,1;1,-5,-3];
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b = [17;0;13;];
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U = A
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L = eye(3);
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for i = [1:length(A)-1]
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for j = [i+1: length(A)]
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L(j,i) = U(j,i)/U(i,i);
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U(j, :) = -U(j,i)/U(i,i) * U(i, :) + U(j, :);
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endfor
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endfor
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U
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L
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#another for loop that's like we create another matrix for Z
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L*U\b
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