Function: quadunit
Section: number_theoretical
C-Name: quadunit
Prototype: G
Help: quadunit(D): fundamental unit of the quadratic field of discriminant D
 where D must be positive.
Doc: fundamental unit\sidx{fundamental units} of the
 real quadratic field $\Q(\sqrt D)$ where  $D$ is the positive discriminant
 of the field. If $D$ is not a fundamental discriminant, this probably gives
 the fundamental unit of the corresponding order. $D$ must be an integer
 congruent to 0 or 1 modulo 4, which is not a square; the result is a
 quadratic number (see \secref{se:quadgen}).