Defining private functions based on the large amount of the Expression Calculator's mathematical inventory is extremely easy. You can call the user defined functions window by pressing the F2 key in the input box, or by choosing User Defined Functions command from the functions menu.
There's a list of a dozen functions defined for demonstration purposes, which include definitions ranging from simple true or false to more complex Fresnel integrals and the Dawson functions. You cannot change existing built-in functions.
To define a new function, fill in a new row in the functions table with the following information:
Choose a unique function name that does not contain numbers and/or other special characters.
Enter the function variables , a list of parameters to the function.
Enter the function definition , the expression to be calculated.
For example, to define a NewSum function of three arguments, x, y, and z, enter NewSum as the function name, xyz as the variables and x + y + z as the function definition.
You can define constants by leaving the variables field blank and using a numeric value as the function definition.
Adding user functions does not evaluate or analyze them. This is done during the calculation only. A name redefinition overwrites previous choices.
The User-Defined Functions table allows you to Update the changes, Reset the definitions, which clears the current table, and to Cancel the changes. You can also Remove an individual definition.
User-defined functions are kept in the local registry and are available during the next session of the Expression Calculator. Saving the calculations or loading them saves and updates the user functions accordingly.