Why aren't these eigenvectors orthogonal?











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As far as I know, the matrix: $$M = begin{pmatrix}1 & 0 & isqrt{3} \ 0 & 2 & 0 \ -isqrt{3} & 0 & 3 end{pmatrix} $$



Is hermitian with eigenvalues: $lambda_1 = 0, lambda_2 = 2, lambda_3 = 4$.



And corresponding eigenvectors:
$V_{lambda_1 = 0} = begin{pmatrix}-isqrt{3} \ 0 \ 1end{pmatrix} $,
$V_{lambda_2 = 2} = begin{pmatrix}0\ 1 \ 0end{pmatrix} $,
$V_{lambda_3 = 4} = begin{pmatrix}dfrac{i}{sqrt{3}}\ 0 \ 1end{pmatrix} $



Since these are eigenvectors of distinct eigenvalues they should be orthogonal but the first and third are not orthogonal.



Why is this?










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    Maybe they are hermitian orthogonal.
    – Charlie Frohman
    Nov 19 at 16:55















up vote
0
down vote

favorite












As far as I know, the matrix: $$M = begin{pmatrix}1 & 0 & isqrt{3} \ 0 & 2 & 0 \ -isqrt{3} & 0 & 3 end{pmatrix} $$



Is hermitian with eigenvalues: $lambda_1 = 0, lambda_2 = 2, lambda_3 = 4$.



And corresponding eigenvectors:
$V_{lambda_1 = 0} = begin{pmatrix}-isqrt{3} \ 0 \ 1end{pmatrix} $,
$V_{lambda_2 = 2} = begin{pmatrix}0\ 1 \ 0end{pmatrix} $,
$V_{lambda_3 = 4} = begin{pmatrix}dfrac{i}{sqrt{3}}\ 0 \ 1end{pmatrix} $



Since these are eigenvectors of distinct eigenvalues they should be orthogonal but the first and third are not orthogonal.



Why is this?










share|cite|improve this question


















  • 1




    Maybe they are hermitian orthogonal.
    – Charlie Frohman
    Nov 19 at 16:55













up vote
0
down vote

favorite









up vote
0
down vote

favorite











As far as I know, the matrix: $$M = begin{pmatrix}1 & 0 & isqrt{3} \ 0 & 2 & 0 \ -isqrt{3} & 0 & 3 end{pmatrix} $$



Is hermitian with eigenvalues: $lambda_1 = 0, lambda_2 = 2, lambda_3 = 4$.



And corresponding eigenvectors:
$V_{lambda_1 = 0} = begin{pmatrix}-isqrt{3} \ 0 \ 1end{pmatrix} $,
$V_{lambda_2 = 2} = begin{pmatrix}0\ 1 \ 0end{pmatrix} $,
$V_{lambda_3 = 4} = begin{pmatrix}dfrac{i}{sqrt{3}}\ 0 \ 1end{pmatrix} $



Since these are eigenvectors of distinct eigenvalues they should be orthogonal but the first and third are not orthogonal.



Why is this?










share|cite|improve this question













As far as I know, the matrix: $$M = begin{pmatrix}1 & 0 & isqrt{3} \ 0 & 2 & 0 \ -isqrt{3} & 0 & 3 end{pmatrix} $$



Is hermitian with eigenvalues: $lambda_1 = 0, lambda_2 = 2, lambda_3 = 4$.



And corresponding eigenvectors:
$V_{lambda_1 = 0} = begin{pmatrix}-isqrt{3} \ 0 \ 1end{pmatrix} $,
$V_{lambda_2 = 2} = begin{pmatrix}0\ 1 \ 0end{pmatrix} $,
$V_{lambda_3 = 4} = begin{pmatrix}dfrac{i}{sqrt{3}}\ 0 \ 1end{pmatrix} $



Since these are eigenvectors of distinct eigenvalues they should be orthogonal but the first and third are not orthogonal.



Why is this?







eigenvalues-eigenvectors






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asked Nov 19 at 16:52









Rzmwood

61




61








  • 1




    Maybe they are hermitian orthogonal.
    – Charlie Frohman
    Nov 19 at 16:55














  • 1




    Maybe they are hermitian orthogonal.
    – Charlie Frohman
    Nov 19 at 16:55








1




1




Maybe they are hermitian orthogonal.
– Charlie Frohman
Nov 19 at 16:55




Maybe they are hermitian orthogonal.
– Charlie Frohman
Nov 19 at 16:55










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They are orthogonal. begin{align}V_0^HV_2&=0\ V_2^HV_4&=0\ V_0^HV_4&=begin{pmatrix}isqrt3&0&1end{pmatrix}cdotbegin{pmatrix}frac i{sqrt3}\ 0\ 1end{pmatrix}=0end{align}






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  • I did not check that the original eigenvectors are OK, but there is a sign difference in the top term of your vertical vector.
    – Andrei
    Nov 19 at 17:00










  • @Andrei Like the one you do when you take the Hermitian of something?
    – Saucy O'Path
    Nov 19 at 17:01












  • Ah! Thank you so much
    – Rzmwood
    Nov 19 at 17:02










  • @SaucyO'Path thanks. I somehow missed that.
    – Andrei
    Nov 19 at 17:07











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They are orthogonal. begin{align}V_0^HV_2&=0\ V_2^HV_4&=0\ V_0^HV_4&=begin{pmatrix}isqrt3&0&1end{pmatrix}cdotbegin{pmatrix}frac i{sqrt3}\ 0\ 1end{pmatrix}=0end{align}






share|cite|improve this answer





















  • I did not check that the original eigenvectors are OK, but there is a sign difference in the top term of your vertical vector.
    – Andrei
    Nov 19 at 17:00










  • @Andrei Like the one you do when you take the Hermitian of something?
    – Saucy O'Path
    Nov 19 at 17:01












  • Ah! Thank you so much
    – Rzmwood
    Nov 19 at 17:02










  • @SaucyO'Path thanks. I somehow missed that.
    – Andrei
    Nov 19 at 17:07















up vote
0
down vote













They are orthogonal. begin{align}V_0^HV_2&=0\ V_2^HV_4&=0\ V_0^HV_4&=begin{pmatrix}isqrt3&0&1end{pmatrix}cdotbegin{pmatrix}frac i{sqrt3}\ 0\ 1end{pmatrix}=0end{align}






share|cite|improve this answer





















  • I did not check that the original eigenvectors are OK, but there is a sign difference in the top term of your vertical vector.
    – Andrei
    Nov 19 at 17:00










  • @Andrei Like the one you do when you take the Hermitian of something?
    – Saucy O'Path
    Nov 19 at 17:01












  • Ah! Thank you so much
    – Rzmwood
    Nov 19 at 17:02










  • @SaucyO'Path thanks. I somehow missed that.
    – Andrei
    Nov 19 at 17:07













up vote
0
down vote










up vote
0
down vote









They are orthogonal. begin{align}V_0^HV_2&=0\ V_2^HV_4&=0\ V_0^HV_4&=begin{pmatrix}isqrt3&0&1end{pmatrix}cdotbegin{pmatrix}frac i{sqrt3}\ 0\ 1end{pmatrix}=0end{align}






share|cite|improve this answer












They are orthogonal. begin{align}V_0^HV_2&=0\ V_2^HV_4&=0\ V_0^HV_4&=begin{pmatrix}isqrt3&0&1end{pmatrix}cdotbegin{pmatrix}frac i{sqrt3}\ 0\ 1end{pmatrix}=0end{align}







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Nov 19 at 16:59









Saucy O'Path

5,6161626




5,6161626












  • I did not check that the original eigenvectors are OK, but there is a sign difference in the top term of your vertical vector.
    – Andrei
    Nov 19 at 17:00










  • @Andrei Like the one you do when you take the Hermitian of something?
    – Saucy O'Path
    Nov 19 at 17:01












  • Ah! Thank you so much
    – Rzmwood
    Nov 19 at 17:02










  • @SaucyO'Path thanks. I somehow missed that.
    – Andrei
    Nov 19 at 17:07


















  • I did not check that the original eigenvectors are OK, but there is a sign difference in the top term of your vertical vector.
    – Andrei
    Nov 19 at 17:00










  • @Andrei Like the one you do when you take the Hermitian of something?
    – Saucy O'Path
    Nov 19 at 17:01












  • Ah! Thank you so much
    – Rzmwood
    Nov 19 at 17:02










  • @SaucyO'Path thanks. I somehow missed that.
    – Andrei
    Nov 19 at 17:07
















I did not check that the original eigenvectors are OK, but there is a sign difference in the top term of your vertical vector.
– Andrei
Nov 19 at 17:00




I did not check that the original eigenvectors are OK, but there is a sign difference in the top term of your vertical vector.
– Andrei
Nov 19 at 17:00












@Andrei Like the one you do when you take the Hermitian of something?
– Saucy O'Path
Nov 19 at 17:01






@Andrei Like the one you do when you take the Hermitian of something?
– Saucy O'Path
Nov 19 at 17:01














Ah! Thank you so much
– Rzmwood
Nov 19 at 17:02




Ah! Thank you so much
– Rzmwood
Nov 19 at 17:02












@SaucyO'Path thanks. I somehow missed that.
– Andrei
Nov 19 at 17:07




@SaucyO'Path thanks. I somehow missed that.
– Andrei
Nov 19 at 17:07


















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