public double dot( Vector3D_F64 a ) {
		return x * a.x + y * a.y + z * a.z;
	}
public double dot( Vector3D_F64 a ) {
		return x * a.x + y * a.y + z * a.z;
	}
public double dot ( Vector3D_F64 a ) { return x * a . x + y * a . y + z * a . z ; }
Dot product between this and 'a' = this.x * a.x + this.y * a.y + this.z * a.z

@param a A vector
@return dot product.
Dot product between this and a = this . x * a . x + this . y * a . y + this . z * a . z