quadratic form discriminant

The discriminant of a binary quadratic form a u^2 + b u v + c v^2 is defined by d congruent 4a c - b^2. It is equal to four times the corresponding binary quadratic form determinant. Unfortunately, some authors define the discriminant of a binary quadratic form as the negative of d above, so care is needed when consulting the literature.

binary quadratic form | binary quadratic form determinant | class number | positive definite quadratic form | positive semidefinite quadratic form