1, 2. If, provided, providing imply a condition on which something depends. If is general. It may be used to indicate suppositions or hypothetical conditions (often involving doubt or uncertainty): If you like, we can go straight home. If I had known, I wouldn't have gone. If may mean even though: If I am wrong, you are not right. It may mean whenever: If I do not understand, I ask questions. Provided always indicates some stipulation: I will subscribe ten dollars provided ( on the condition ) that you do, too. Provided he goes, we can go along. Providing means the same as provided, that is, just in case some certain thing should happen: We will buy the house, providing ( provided ) we can get a mortgage.

Did you mean IFS?