v.YminusX.Select(&a.YminusX, &b.YminusX, cond) v.T2d.Select(&a.T2d, &b.T2d, cond) return v } // CondNeg negates v if cond == 1 and leaves it unchanged if cond == 0. func (v *projCached) CondNeg(cond int) *projCached { v.YplusX.Swap(&v.YminusX, cond) v.T2d.Select(new(field.Element).Negate(&v.T2d), &v.T2d, cond) return v } // CondNeg negates v if cond == 1 and leaves it unchanged if cond == 0. func (v *affineCached) CondNeg(cond int) *affineCached { v.YplusX.Swap(&v.YminusX, cond) v.T2d.Select(new(field.Elem...