func (e *P521Element) Mul(t1, t2 *P521Element) *P521Element {
	p521Mul(&e.x, &t1.x, &t2.x)
	return e
}

// Square sets e = t * t, and returns e.
func (e *P521Element) Square(t *P521Element) *P521Element {
	p521Square(&e.x, &t.x)
	return e
}

// Select sets v to a if cond == 1, and to b if cond == 0.
func (v *P521Element) Select(a, b *P521Element, cond int) *P521Element {

	out1[7] = x1015
	out1[8] = x1016
}

// p521Square squares a field element in the Montgomery domain.
//
// Preconditions:
//
//	0 ≤ eval arg1 < m
//
// Postconditions:
//
//	eval (from_montgomery out1) mod m = (eval (from_montgomery arg1) * eval (from_montgomery arg1)) mod m
//	0 ≤ eval out1 < m
func p521Square(out1 *p521MontgomeryDomainFieldElement, arg1 *p521MontgomeryDomainFieldElement) {