2019-06-16 00:40:29 +0200 | answered a question | Series expansion for theta function of even lattice There is a simpler explanation, which is that the quadratic form Maps to the matrix Which is equivalent to the symmetric matrix Which can be gotten with A.Gram_matrix(). The A.matrix() function listed in the answer above is the Hessian, which is double the Gram matrix. The documentation for Gram matrix gives as an example a Quadratic form with diagonal matrix. Should probably be updated to include off-diagonal terms to make this clearer. |

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