### Finding the class number h(d) of binary quadratic forms of negative discriminant d

Here d ≡ 0 (mod 4) or 1 (mod 4).

If flag value 1 is entered below, we print only the primitive forms.

If flag value 0 is entered, we print primitive and imprimitive forms.

h(d) is returned in each case.

H. Davenport's *Higher Arithmetic* has a table of forms, which
lists the imprimitive ones with an asterisk.

If d is the discriminant of an imaginary quadratic field K, then the primitive forms class-number h(d) is also the class number of K.
(See Henri Cohen's Algorithm 5.3.5, p. 228, *A course in computational number theory*, First Edition.)

*Last modified 12th May 2003*

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