Calculate NDVI

Hi everyone. I have a question, When calculate NDVI I used foat function.
-and what is foat function mean ? Thank you very much

referring to SNAP I can’t find anything like foat.
Could you give a bit more information on your problem?

For the case you mean “float”: Float is the data type which allows decimal positions. They are needed because the NDVI ranges between -1 and 1.