It says that; Let f be continuous on [a,b]. Define a new function F on [a,b] as follows; For all x in [a,b], F(x)=int(a-x)f=int(a-x)f(t)dt. My teacher likes to call this the windshield wiper function, unfortunetly i missed the class in which he told us this. But from the notes, there isn't much explaination. So i was wondering if anyone knows what this function actually says, since i was trying to find in my book too but its hard without knowning the name used in texts, if there is such a thing.