sum using loops-CodePudding

I want to sum (1/3) (3/5) ⋯ (99/101) using loops in R I have tried this and I want to check if its right and is there other solutions also if we can do it with for loops and repeat loops.

sum <- 0
i <- 1
j <- 3
while (i<=99 && j<=101 ) {
  sum <- sum i/j
  i <- i 2
  j <- j 2
}
print(sum)

CodePudding user response：

Yes, it is correct. Although you can also do

sum <- 0
i <- 1
while (i<=99) {
  sum <- sum i/(i 2)
  i <- i 2
}
sum

sum <- 0
for (i in seq(1,99,2)) {
  sum <- sum i/(i 2)
}
sum

sum <- 0
i <- 1
repeat {
  sum <- sum i/(i 2)
  if (i == 99) break
  i <- i   2
}
sum

i <- seq(1,99,2)
sum(i / (i   2))

Ah, you'd better use another name than sum for your variable.

CodePudding user response：

Your implementation seems fine. If you want to try for loops it can be

sum <- 0
for (i in seq(1, 99, 2)){
    sum <- sum   i/(i 2)
}

CodePudding user response：

We can use the idea of odd numbers formula where 2*n - 1 and 2*n 1 are two consecutive odd numbers

result <- 0
for(i in 1:50){
    result <- result   (2*i - 1)/(2*i   1)
}

output

result

#>[1] 46.10465