How to transform a square orthogonal matrix into a norm-preserving non-square matrix?












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Assume we have an arbitrary $n times n$ orthogonal matrix of real values. How can you transfer such a matrix into an $m times n$ non-square matrix (where $m < n$) which also preserves the norm of any $n$ sized vector which would be multiplied by it? What would be the least computationally expensive way of doing such transformation?










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  • $begingroup$
    When $m<n$, there is no $mtimes n$ matrix $Ax$ such that $|Ax|=|x|$ for all $x$.
    $endgroup$
    – Rahul
    Jan 30 at 7:38
















0












$begingroup$


Assume we have an arbitrary $n times n$ orthogonal matrix of real values. How can you transfer such a matrix into an $m times n$ non-square matrix (where $m < n$) which also preserves the norm of any $n$ sized vector which would be multiplied by it? What would be the least computationally expensive way of doing such transformation?










share|cite|improve this question









$endgroup$












  • $begingroup$
    When $m<n$, there is no $mtimes n$ matrix $Ax$ such that $|Ax|=|x|$ for all $x$.
    $endgroup$
    – Rahul
    Jan 30 at 7:38














0












0








0





$begingroup$


Assume we have an arbitrary $n times n$ orthogonal matrix of real values. How can you transfer such a matrix into an $m times n$ non-square matrix (where $m < n$) which also preserves the norm of any $n$ sized vector which would be multiplied by it? What would be the least computationally expensive way of doing such transformation?










share|cite|improve this question









$endgroup$




Assume we have an arbitrary $n times n$ orthogonal matrix of real values. How can you transfer such a matrix into an $m times n$ non-square matrix (where $m < n$) which also preserves the norm of any $n$ sized vector which would be multiplied by it? What would be the least computationally expensive way of doing such transformation?







linear-algebra matrices numerical-linear-algebra






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asked Jan 30 at 7:23









AnonAnon

1




1












  • $begingroup$
    When $m<n$, there is no $mtimes n$ matrix $Ax$ such that $|Ax|=|x|$ for all $x$.
    $endgroup$
    – Rahul
    Jan 30 at 7:38


















  • $begingroup$
    When $m<n$, there is no $mtimes n$ matrix $Ax$ such that $|Ax|=|x|$ for all $x$.
    $endgroup$
    – Rahul
    Jan 30 at 7:38
















$begingroup$
When $m<n$, there is no $mtimes n$ matrix $Ax$ such that $|Ax|=|x|$ for all $x$.
$endgroup$
– Rahul
Jan 30 at 7:38




$begingroup$
When $m<n$, there is no $mtimes n$ matrix $Ax$ such that $|Ax|=|x|$ for all $x$.
$endgroup$
– Rahul
Jan 30 at 7:38










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