main/src/georegression/struct/point/Vector3D_F64.java
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.