Is it possible for a $3 times 3$ matrix to have rank 1 but not be diagonalizable?











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Is it possible for a $3 times 3$ matrix to have rank $1$ but not be diagonalizable?




If the matrix only has the top left entry, then obviously it is already diagonal. But what about other two entries? I know that a condition for the matrix to be diagonalizable is for the matrix to have $3$ linearly independent eigenvectors, but I am unsure how to prove whether that will always be the case for any rank $1$, $3 times 3$ matrix.










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  • 5




    $pmatrix{0&1\0&0}$ is a $2times 2$ matrix of rank $1$ that isn't diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 3:27










  • This might help!
    – Chinnapparaj R
    Nov 27 at 3:28






  • 1




    @LordSharktheUnknown Then it follows that $begin{bmatrix}0 & 0 & 1 \0 & 0 & 0\0 & 0 & 0end{bmatrix}$ is not diagonalizable, correct? (Since there is only one eigenvector)
    – SolidSnackDrive
    Nov 27 at 4:36












  • @SolidSnackDrive That's not a square matrix, so cannot be diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 4:37










  • Sorry, please see my edit.
    – SolidSnackDrive
    Nov 27 at 4:37















up vote
2
down vote

favorite













Is it possible for a $3 times 3$ matrix to have rank $1$ but not be diagonalizable?




If the matrix only has the top left entry, then obviously it is already diagonal. But what about other two entries? I know that a condition for the matrix to be diagonalizable is for the matrix to have $3$ linearly independent eigenvectors, but I am unsure how to prove whether that will always be the case for any rank $1$, $3 times 3$ matrix.










share|cite|improve this question




















  • 5




    $pmatrix{0&1\0&0}$ is a $2times 2$ matrix of rank $1$ that isn't diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 3:27










  • This might help!
    – Chinnapparaj R
    Nov 27 at 3:28






  • 1




    @LordSharktheUnknown Then it follows that $begin{bmatrix}0 & 0 & 1 \0 & 0 & 0\0 & 0 & 0end{bmatrix}$ is not diagonalizable, correct? (Since there is only one eigenvector)
    – SolidSnackDrive
    Nov 27 at 4:36












  • @SolidSnackDrive That's not a square matrix, so cannot be diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 4:37










  • Sorry, please see my edit.
    – SolidSnackDrive
    Nov 27 at 4:37













up vote
2
down vote

favorite









up vote
2
down vote

favorite












Is it possible for a $3 times 3$ matrix to have rank $1$ but not be diagonalizable?




If the matrix only has the top left entry, then obviously it is already diagonal. But what about other two entries? I know that a condition for the matrix to be diagonalizable is for the matrix to have $3$ linearly independent eigenvectors, but I am unsure how to prove whether that will always be the case for any rank $1$, $3 times 3$ matrix.










share|cite|improve this question
















Is it possible for a $3 times 3$ matrix to have rank $1$ but not be diagonalizable?




If the matrix only has the top left entry, then obviously it is already diagonal. But what about other two entries? I know that a condition for the matrix to be diagonalizable is for the matrix to have $3$ linearly independent eigenvectors, but I am unsure how to prove whether that will always be the case for any rank $1$, $3 times 3$ matrix.







linear-algebra eigenvalues-eigenvectors diagonalization






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share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Nov 27 at 3:33









Chinnapparaj R

4,7991825




4,7991825










asked Nov 27 at 3:24









SolidSnackDrive

1808




1808








  • 5




    $pmatrix{0&1\0&0}$ is a $2times 2$ matrix of rank $1$ that isn't diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 3:27










  • This might help!
    – Chinnapparaj R
    Nov 27 at 3:28






  • 1




    @LordSharktheUnknown Then it follows that $begin{bmatrix}0 & 0 & 1 \0 & 0 & 0\0 & 0 & 0end{bmatrix}$ is not diagonalizable, correct? (Since there is only one eigenvector)
    – SolidSnackDrive
    Nov 27 at 4:36












  • @SolidSnackDrive That's not a square matrix, so cannot be diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 4:37










  • Sorry, please see my edit.
    – SolidSnackDrive
    Nov 27 at 4:37














  • 5




    $pmatrix{0&1\0&0}$ is a $2times 2$ matrix of rank $1$ that isn't diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 3:27










  • This might help!
    – Chinnapparaj R
    Nov 27 at 3:28






  • 1




    @LordSharktheUnknown Then it follows that $begin{bmatrix}0 & 0 & 1 \0 & 0 & 0\0 & 0 & 0end{bmatrix}$ is not diagonalizable, correct? (Since there is only one eigenvector)
    – SolidSnackDrive
    Nov 27 at 4:36












  • @SolidSnackDrive That's not a square matrix, so cannot be diagonalisable.
    – Lord Shark the Unknown
    Nov 27 at 4:37










  • Sorry, please see my edit.
    – SolidSnackDrive
    Nov 27 at 4:37








5




5




$pmatrix{0&1\0&0}$ is a $2times 2$ matrix of rank $1$ that isn't diagonalisable.
– Lord Shark the Unknown
Nov 27 at 3:27




$pmatrix{0&1\0&0}$ is a $2times 2$ matrix of rank $1$ that isn't diagonalisable.
– Lord Shark the Unknown
Nov 27 at 3:27












This might help!
– Chinnapparaj R
Nov 27 at 3:28




This might help!
– Chinnapparaj R
Nov 27 at 3:28




1




1




@LordSharktheUnknown Then it follows that $begin{bmatrix}0 & 0 & 1 \0 & 0 & 0\0 & 0 & 0end{bmatrix}$ is not diagonalizable, correct? (Since there is only one eigenvector)
– SolidSnackDrive
Nov 27 at 4:36






@LordSharktheUnknown Then it follows that $begin{bmatrix}0 & 0 & 1 \0 & 0 & 0\0 & 0 & 0end{bmatrix}$ is not diagonalizable, correct? (Since there is only one eigenvector)
– SolidSnackDrive
Nov 27 at 4:36














@SolidSnackDrive That's not a square matrix, so cannot be diagonalisable.
– Lord Shark the Unknown
Nov 27 at 4:37




@SolidSnackDrive That's not a square matrix, so cannot be diagonalisable.
– Lord Shark the Unknown
Nov 27 at 4:37












Sorry, please see my edit.
– SolidSnackDrive
Nov 27 at 4:37




Sorry, please see my edit.
– SolidSnackDrive
Nov 27 at 4:37















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