This is a paragraph from a book, which I don't understand:(adsbygoogle = window.adsbygoogle || []).push({});

"How many independent parameters are there in a 3x3 matrix? A real 3x3 matrix has 9 entries but if we have the orthogonality constraint,

[tex]RR^T = 1 [/tex]

which corresponds to 6 independent equations because the product

[tex]RR^T[/tex] being the same as [tex]R^TR [/tex], is a symmetrical matrix with 6 independent entries.

As a result, there are 3 (9-6) independent numbers in R."

I can understand why a real 3x3 matrix has 9 entries. But the sentences after that...I don't understand.

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# Homework Help: 3 by 3 matrix with an orthogonality constraint

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