public static double CrossMagnitudeSquared(this IVector a, IVector b)
{
if (a.Count != b.Count) throw new ArgumentException();
return a.LengthSquared() * b.LengthSquared() - Dot(a, b) * Dot(a, b);
}
public static IVector ProjectionOnto(this IVector a, IVector b)
{
return b.Multiply(a.Dot(b) / b.LengthSquared());
}
