search for: numberofcrossings

Hello, If the exact value does not exist in the vector, can I still get at the intersections? Is there a simple way to do this and avoid looping? Seems like there would be a simple R function to do this... Example: vec <- c(5,4,3,2,3,4,5) vec [1] 5 4 3 2 3 4 5 intersect(vec,2.5) numeric(0) I want to get: 2.5 and 2.5 My real data is very large and I don't know the values of anything