I have developed a math parser named uCalc FMP, which allows your programs to evaluate expressions / formulas that are defined at runtime.  In addition to a built-in set of functions/operators, it lets you define an unlimited number of your own functions, operators, variables, constants, etc... 
No provisions were originally made for LabVIEW.  After I redesigned uCalc FMP, a customer recently notified me that the new uCalc version no longer works easily with LabVIEW the way the old uCalc version did. 
I have now created a special LabVIEW wrapper for the new version of uCalc FMP, which will hopefully make it work as easily as before.  However, I have no personal experience with LabVIEW, so I will need some help from LabVIEW users to ensure that the wrapper works correctly. 
The LabVIEW wrapper for uCalc FMP 2.91 can be found at: 
www.ucalc.com/ubb/Forum8/HTML/000021.html 
If you are not familiar with uCalc FMP, you will find more information at: 
www.ucalc.com/ucalcfmp.html 
To download a fully functional copy of uCalc FMP 2.91, visit: 
www.ucalc.com/download.html 
If you want an eval copy of the old version 2.0 of uCalc FMP, the link is: 
www.ucalc.com/mathparser/ucfmp20.zip 
I look forward to hearing from LabVIEW users. 
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Daniel Corbier 
www.ucalc.com