def mynumerator(x): if parent(x) == R: return x return numerator(x) class fastfrac: def __init__(self,top,bot=1): if parent(top) == ZZ or parent(top) == R: self.top = R(top) self.bot = R(bot) elif top.__class__ == fastfrac: self.top = top.top self.bot = top.bot * bot else: self.top = R(numerator(top)) self.bot = R(denominator(top)) * bot def reduce(self): return fastfrac(self.top / self.bot) def sreduce(self): return fastfrac(I.reduce(self.top),I.reduce(self.bot)) def iszero(self): return self.top in I and not (self.bot in I) def isdoublingzero(self): return self.top in J and not (self.bot in J) def __add__(self,other): if parent(other) == ZZ: return fastfrac(self.top + self.bot * other,self.bot) if other.__class__ == fastfrac: return fastfrac(self.top * other.bot + self.bot * other.top,self.bot * other.bot) return NotImplemented def __sub__(self,other): if parent(other) == ZZ: return fastfrac(self.top - self.bot * other,self.bot) if other.__class__ == fastfrac: return fastfrac(self.top * other.bot - self.bot * other.top,self.bot * other.bot) return NotImplemented def __neg__(self): return fastfrac(-self.top,self.bot) def __mul__(self,other): if parent(other) == ZZ: return fastfrac(self.top * other,self.bot) if other.__class__ == fastfrac: return fastfrac(self.top * other.top,self.bot * other.bot) return NotImplemented def __rmul__(self,other): return self.__mul__(other) def __div__(self,other): if parent(other) == ZZ: return fastfrac(self.top,self.bot * other) if other.__class__ == fastfrac: return fastfrac(self.top * other.bot,self.bot * other.top) return NotImplemented def __pow__(self,other): if parent(other) == ZZ: return fastfrac(self.top ^ other,self.bot ^ other) return NotImplemented def isidentity(x): return x.iszero() def isdoublingidentity(x): return x.isdoublingzero() R. = PolynomialRing(QQ,6,order='invlex') I = R.ideal([ mynumerator((uy1^2)-(ux1^3+ua*ux1+ub)) , mynumerator((ux1)-(uX1/uZ1)) ]) ua = fastfrac(ua) ub = fastfrac(ub) ux1 = fastfrac(ux1) uy1 = fastfrac(uy1) uX1 = fastfrac(uX1) uZ1 = fastfrac(uZ1) uX3 = (((uX1^2-ua*uZ1^2)^2-fastfrac(8)*ub*uX1*uZ1^3)) uZ3 = ((fastfrac(4)*uZ1*(uX1^3+ua*uX1*uZ1^2+ub*uZ1^3))) ux3 = (((fastfrac(3)*ux1^2+ua)^2/(fastfrac(2)*uy1)^2-ux1-ux1)).reduce() uy3 = (((fastfrac(2)*ux1+ux1)*(fastfrac(3)*ux1^2+ua)/(fastfrac(2)*uy1)-(fastfrac(3)*ux1^2+ua)^3/(fastfrac(2)*uy1)^3-uy1)).reduce() print isidentity((uy3^2)-(ux3^3+ua*ux3+ub)) print isidentity((ux3)-(uX3/uZ3))