Why use this equation?

I wonder why the equation is needed

v = (0.5 * uramp (x, 0)) - (ustep (x, 1)) - (0.5 * uramp (x, 2));

In order to graph it out as in the figure

Answer 1

[Walter Roberson]

That equation is not needed. There are other ways of producing the same graph.

(The other ways might be more work though.)

[Pichaya Thochampa]

Can you guide me plese