How to deal with floating point errors in R

Question

Consider the following R function

is.sqrt <- function(x, y){
  if(x^2 == y) TRUE
  else FALSE
}

which answers whether x is the square ro

Answer 1

you can use all.equal in your function, which "tests if two objects are 'nearly' equal"

is.sqrt <- function(x, y){
    isTRUE(all.equal(x^2,y)
}


 is.sqrt(sqrt(2), 2)
 # TRUE

 is.sqrt(sqrt(2), 3)
 # FALSE