In agracy2246/MATH4753grac0009: Adam Gracy MATH4753

knitr::opts_chunk$set(echo = TRUE, comment='ws#')

mysd(x)

1. The function takes an argument 'x' which needs to be a Numeric vector.

mysd <- function(x){
  N        <- length(x)
  variance <- sum((x - mean(x))^2) / (N - 1)
  std      <- sqrt(variance)
}

1. Run with given input

L <- 1:20
cat(mysd(L))

1. Compare with builtin sd()

cat("Built in sd():",sd(L), "\nMy function:", mysd(L))

1. Alter function

mysd <- function(x){
  N        <- length(x)
  variance <- sum((x - mean(x))^2) / (N - 1)
  std      <- sqrt(variance)
  list(sd = std, variance = variance)

}

mysd(x = L)

agracy2246/MATH4753grac0009 documentation built on April 26, 2020, 9:39 a.m.