To add a Static UDF (UDF for short) to your modeling kit, just click the Add button on the Static UDFs frame and the UDF Editor appears with the function header already in place.

Then you just have to write the body of the function in the code editor. The code must be in JavaScript and can be rapidly tested for compiling errors by pressing the Test button.

You will notice that the Arity box is disabled and set to zero as all UDFs will occupy leaf nodes in the trees, that is, they behave exactly as terminals.

In the Definition box, you can write a brief description of the function for your future reference. The text you write there will appear in the Definition column of the Static UDFs Tab.

The use of UDFs is a very powerful tool as they allow you to explore inside knowledge about your problem and design useful building blocks that are essential to design more complex logic circuits. For instance, suppose you wanted to design a logic circuit for the 11-multiplexer using the 6-multiplexer as a basic building block. So you design a UDF for the 6-multiplexer and then use this new UDF as an extra building block in your modeling kit. The advantage of well designed UDFs is that they make the discovery of more complex circuits composed of several simpler units much easier.