1 | initial version |

This can be accomplished with the Heaviside step function, something that should be familiar in engineering (especially electrical engineering) contexts. Try `sage: heaviside?`

to see the docsting. I'll give a one variable example that you can easily turn into a two variable example for your application:

```
sage: g(x) = (1-heaviside(x-pi/2)) * heaviside(x + pi/2)
sage: plot(g(x), (x, -pi, pi))
sage: plot( g(x) * cos(x), (x, -pi, pi))
```

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