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Can anyone recommend a good reference for brushing up on quadratic forms?

They keep coming up (quite naturally of course) in the context of differential geometry and I find I am rustier than I remembered. I've looked through a large number of linear algebra books and found mostly short sections that cover the basics: reduction to canonical form and Sylvester's criterion, but nothing that goes much beyond. I've also found others that get quite deep into the issue from a more abstract algebraic point of view, but they seemed like they would require a significant detour from my current studies. Does anyone know any books that provide something in between?

(Something available as a pdf that I can download/buy online would be perfect, but any other reference would help greatly as well).

Thanks in advance

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    @Sanchez: I'm not sure, I don't know what I don't know. The books I found (I truly looked through quite a few) did not seem like the best choices, it occurred to me that asking the community for suggestions is probably better than randomly trying books.2013-01-01

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Here are three PDFs that I became aware of during my own searches on this question some time ago:

http://www.math.jussieu.fr/~karpenko/publ/Kniga.pdf

http://www.math.miami.edu/~armstrong/685fa12/pete_clark.pdf

http://www.math.uconn.edu/~kconrad/blurbs/linmultialg/bilinearform.pdf

I think a "middle" text that is both affordable and easy to obtain is Jacobson's Basic Algebra I Chapter 6 on metric vector spaces.

T.Y. Lam's Introduction to quadratic forms also sounds like a good bet. I say that because I haven't read this book yet, but judging from the author's other books, I bet this one must be good too. Good luck!

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    Perfect - thank you! I especially like pete_clark.pdf2013-01-01