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  1. What do Q and R stand for?

  2. Why must the diagonal entries of R be positive instead of just nonzero?

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    $A=QR$, $Q$ is an orthogonal matrix and $R$ is an upper triangular matrix.2012-11-28
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    Thanks. I know that. I mean what names do Q and R stand for? Queer Rainbow? Quixotic Renegade?2012-11-28
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    See [here](http://en.wikipedia.org/wiki/QR_decomposition) under "computing the $QR$ decomposition" and you will find the answer for part $(2)$ of your question.2012-11-28
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    +1 for "what do Q and R stand for". My **guess** was that ORthogonal starts with O and tRiangulaR ends with R, but OR is a logical operator so they call it QR. Alternatively QR are two subsequent letters and M (matrix), n (count) and P (often used in definitions here) are used. In that case you would start namefinding from `LU`.2013-01-30

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