Piecewise Parametric Example

Any of the functions available in Mechanical Expressions can be piecewise, including parametric functions.  Take this square for example.

1. Click the Draw / Function tool  
2. Select Parametric from the drop down Type window.
3. Enter the first value (side) for the square and the range for the parameter values - hit enter.  Don't worry about the shape of the function, it's not defined yet.
4. Double-click the function and select the x value
5. Click the Piecewise icon
6. Enter the x values for each side of the square.   When you run out of gray boxes, click the Piecewise icon again to get another row.
7. Now do the same for the y value, select the T parameter and click the Piecewise icon 3 times. Use the arrow keys on your keyboard or your mouse to move to the next gray box.

Here is the function: