calculate (String, Object [], INodeHelper) AwareIM Documentation

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{{tag>Index Programmers_Reference Methods IFunctionLibrary_Interface Calculate}}

====calculate (String, Object [], INodeHelper)====
<code java>public Object calculate (String functionName, Object [] parameters, INodeHelper helper)</code>

This method is what the function is all about – it performs the required calculation and returns the result.

===Parameters===
|''functionName''|the name of the function in the library that needs to be calculated|
|''parameters''|the values of function parameters as specified in a rule where the function is used. The given array contains Java objects corresponding to different attribute types (''String'', ''Integer'', ''DateHolder'' etc – see a complete list in the [[docs:3500:appendix_a|Appendix A]])|
|''helper''|a call-back interface. Should not be used by custom function libraries.|

===Returns===
The result of the calculation as a Java object of the type corresponding to the attribute types – see [[docs:3500:appendix_a|Appendix A]]. If the function value cannot be calculated for whatever reason (for example, the number of parameters or their types are wrong), ''null'' should be returned.

index programmers reference methods ifunctionlibrary interface calculate