Michael Wijaya
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 Nov29 awarded Critic Jul19 awarded Enthusiast Jul15 awarded Nice Answer Jul14 comment Minimum of $n$? $123456789x^2 - 987654321y^2 =n$ ($x$,$y$ and $n$ are positive integers) I don't think Dr. Weissmann has gotten to Conway's topograph yet in his blog. If he's written about it somewhere, I'd love to read it. My understanding is that he is the authority in the topograph method and its generalizations. Jul13 comment Solve $37x^2-113y^2=n$ @Hecke One of my favorite quotes: "To improve upon Hecke, in a treatment along classical lines of the theory of algebraic numbers, would be a futile and impossible task." --- André Weil Jul13 comment Solve $37x^2-113y^2=n$ @Hecke There was a gap in my proof because I did not take into account the fact that $16724$ is not a fundamental discriminant. I think I fixed it. By the way, does your nickname have anything to do with Erich Hecke? Jul13 revised Solve $37x^2-113y^2=n$ Fixed gap in proof from not considering fundamental discriminant. Rearranged material, added section on further comments. Jul13 awarded Yearling Jul13 answered Solve $37x^2-113y^2=n$ Jun15 comment Matrix of quadratic form has to be symmetric? The section you linked to is about forms over $\mathbb{R}$, which has characteristic not equal to 2. Over such fields, we do not get any new quadratic form by considering non-symmetric matrices because we can divide by 2. So $\begin{pmatrix} a & b \\ c & d \end{pmatrix}$ gives the same quadratic form as $\begin{pmatrix} a & \frac{b+c}{2} \\ \frac{b+c}{2} & d \end{pmatrix}$. Jun7 revised Diagonalising quadratic form added 388 characters in body Jun7 answered Diagonalising quadratic form May27 answered How to find $A$ such that $A^2$ is the zero matrix? Mar28 awarded Editor Mar28 revised Minimum of $n$? $123456789x^2 - 987654321y^2 =n$ ($x$,$y$ and $n$ are positive integers) Provide a better example of the versatility of Conway's topograph Mar28 awarded Teacher Mar28 answered Minimum of $n$? $123456789x^2 - 987654321y^2 =n$ ($x$,$y$ and $n$ are positive integers) Feb24 awarded Supporter