∂⁡(f,g,h)∂⁡(x,y,z)=|∂⁡f/∂⁡x∂⁡f/∂⁡y∂⁡f/∂⁡z∂⁡g/∂⁡x∂⁡g/∂⁡y∂⁡g/∂⁡z∂⁡h/∂⁡x∂⁡h/∂⁡y∂⁡h/∂⁡z|,