Hi, The conditions are not very clear. For example, it is not mentioned whether vectors are of same length or not.? Assuming the former case: fun1 <- function(x,y){ ?if(length(x)==length(y) & length(x)%%2==0){ ?res <- x+y ?} ?else if(length(x)==length(y) & length(x)%%2==1){ ?res <- abs(x-y) } else print("Lengths are not same") res } ?vec1 <- 1:10 ?vec2 <- 11:20 ?vec3 <- 1:9 ?vec4 <- 10:18 ?fun1(vec3,vec4) ?fun1(vec1,vec2) fun1(vec1,vec3) A.K. Hi, I'm new on this forum, and I need some help with for loop. I have to write loop that will add two vectors, if they are even. Even if they are odd, it must subtract the two vectors.