Sedona XPRESSion Evaluator Reference Guide

Custom User-Defined Functions

The XPRESSion Evaluator provides a very powerful mechanism for creating, storing, and manipulating custom user-defined functions. Custom functions can be employed to encapsulate logical and arithmetic functions that are not part of the built-in XPRESSion Evaluator library (described above). Custom functions can be arbitrarily complex, just as in any expression, and may refer to any of the built-in functions as well as to any other user-defined functions.

Once created, custom functions can appear in any expression, just like any other built-in function. Custom functions are defined by the user in the following format:

FuncName(arg1, arg2, arg3, ...) = <expr>

where FuncName and arg<n> can be any valid <identifier>, and <expr> can be an arbitrarily complex expression written in terms of arg1...argN.


MyFunc(a, b, c) = a * log(b - c)

YourFunc(one, two) = MyFunc(one, two, 3.14) ^ 2

OurFunc(alpha, beta, gamma) = exp(YourFunc(alpha/gamma, beta) - 1)

Further information on defining and storing custom functions appears later in the descriptions of the API VIs designed to create, store, and manipulate custom user-defined functions.

In addition to the above elements, the XPRESSion Evaluator implements a host of built-in functions. Note that many of these are the same functions available in the LabVIEW Formula Node. See the LabVIEW User Manual for a detailed description of these functions.