Function: qfbhclassno
Section: number_theoretical
C-Name: hclassno
Prototype: G
Help: qfbhclassno(x): Hurwitz-Kronecker class number of x>0.
Doc: \idx{Hurwitz class number} of $x$, when
 $x$ is nonnegative and congruent to 0 or 3 modulo 4, and $0$ for other
 values. For $x > 5\cdot 10^{5}$, we assume the GRH, and use \kbd{quadclassunit}
 with default parameters.
 \bprog
 ? qfbhclassno(1) \\ not 0 or 3 mod 4
 %1 = 0
 ? qfbhclassno(3)
 %2 = 1/3
 ? qfbhclassno(4)
 %3 = 1/2
 ? qfbhclassno(23)
 %4 = 3
 @eprog
