Loops

3 types of loops:     for    while    repeat
inside loops useful functions are:    next    break

The structure of the for loop is illustrated:

sum1 <- sum2 <- 0
for (i in 1:200) {
     sum1 <- sum1+1/i
   sum2 <- sum2+(1/i)^2
}

The above is not good R programming though, such a computation is better done using vector-thinking:

sum1 <- 1/1:200; sum2 <- 1/(1:200)^2

Often as in the above example, for loops can be avoided by vector-thinking.

The syntax of a while loop:

i<- sum1 <- sum2 <- 0
while (i < 200) {
   i <- i+1
     sum1 <- sum1+1/i
   sum2 <- sum2+(1/i)^2
}

and a repeat loop to do the above:

i <- sum1 <- sum2 <- 0
repeat {
   i <- i+1
     sum1 <- sum1+1/i
   sum2 <- sum2+(1/i)^2
   if (i >= 200) break()
}