I am studying this equation:
$$\frac{x + y - abs(x - y)}{2}$$
If I plotted it looks like this Equation in 3D between [0 1], a rectangular pyramid.
![Equation in 3D between [0 1]](https://i.stack.imgur.com/Gxgax.png){kind=link}
I wanted to plot the same shape but wanted it to be on the opposite side with the reverse of this function. Like in this figure
What will the equation of this shape be? or how to change the original equation so then I can generate the shape on the top right?