Qfb

Function: Qfb
Section: conversions
C-Name: Qfb0
Prototype: GDGDG
Help: Qfb(a,{b},{c}): binary quadratic form a*x^2+b*x*y+c*y^2.
Doc: creates the binary quadratic form\sidx{binary quadratic form}
 $ax^2+bxy+cy^2$. Negative definite forms are not implemented,
 use their positive definite counterpart instead.
 The syntax Qfb([a,b,c]) is also accepted.