@Override
    public Quaterniond mul(double a) {
        return new Quaterniond(x * a, y * a, z * a, w * a);
    }
@Override
    public Quaterniond mul(double a) {
        return new Quaterniond(x * a, y * a, z * a, w * a);
    }
@ Override public Quaterniond mul ( double a ) { return new Quaterniond ( x * a , y * a , z * a , w * a ) ; }
Multiplies the components of this quaternion by a double scalar.

@param a The multiplication scalar
@return A new quaternion, which has each component multiplied by the scalar
Multiplies the components of this quaternion by a double scalar .