411 REFERENCE · Wikibooks
Linear Algebra and the C Language/a0n8
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The spectral decomposition:
The matrix A and the inverse matrix of A have the same eigenvectors but arranged in reverse order
c00a.c ... ... ... ... ... ... Octave
The application
b1r1 + b2r2 + b3r3 = Ide (The b_r_ are projectors.)
c00b.c ... ... ... ... ... ... Octave
b*: The columns of the eigenvectors of A
r*: The rows of eigenvectors of the inverse of A
E1 b1r1 + E2 b2r2 + E3 b3r3 = A
c00c.c ... ... ... ... ... ... Octave
E*: The eigenvalues of A
b1r1**2 = b1r1; ... ... ... b1r1**3 = b1r1; ... ... ... b1r1**P = b1r1;
c00d.c ... ... ... ... ... ... Octave
Several consecutive projections, (b_r_**P), give the same result
b1r1 * b3r3 = 0; ... ... ... b1r1 * b2r2 = 0; ... ... ... b2r2 * b3r3 = 0;
c00e.c ... ... ... ... ... ... Octave
The projectors b_r_ are orthogonal to each other
E1**2 b1r1 + E2**2 b2r2 + E3**2 b3r3 = A**2
c00f.c ... ... ... ... ... ... Octave
Calculate the power n of A with the power n of each of the eigenvalues
1/E1 b1r1 + 1/E2 b2r2 + 1/E3 b3r3 = inv(A)
c00g.c ... ... ... ... ... ... Octave
Calculate the inverse of A with the inverse of each of the eigenvalues