Pelle's solution is certainly the natural way to do this in LabVIEW. 🙂
You have to be careful though, because if the input is the result of a computation involving fractions, the DBL could be off by a bit or so, leading to unexpected results.
Since you posted in the mathscript forum, could it be you are looking for a mathscript solution?
The current solution turns on a plain LED indicator, but you want to turn on an LCD. Are you looking for a hardware solution to physically turn something on or off? What should be displayed on the LCD?