Question

Write a function that uses the formulas below

𝑚𝑒𝑎𝑛 = (𝑥1 + 𝑥2 + ⋯ + 𝑥𝑁)/𝑁

𝑣𝑎𝑟𝑖𝑎𝑛𝑐𝑒 =

𝑠(𝑥1 − 𝑥̅)2 + (𝑥2 − 𝑥̅)2 + ⋯ + (𝑥𝑁 − 𝑥̅)2

𝑁

𝑠𝑑 = √𝑣𝑎𝑟𝑖𝑎𝑛𝑐𝑒

a. Returns the mean (i.e. average) 𝑥̅, of the values in an array by value.

b. Returns the variance of the data set by reference.

c. Returns the standard deviation of the data set by reference. 

Answer 1

#include <iostream>


float get_mean(float* arr, int n) {
    float mean{ 0 };
    for (int i = 0; i < n; i++) {
        mean += arr[i];
    }
    return mean/n;
}
float get_variance(float* arr, int n) {
    float variance{ 0 };
    float mean = get_mean(arr, n);
    for (int i = 0; i < n; i++) {
        variance += pow((arr[i] - mean), 2);
    }
    return variance/n;
}


float get_deviation(float* arr, int n) {
    float deviation{ 0 };
    deviation = pow(get_variance(arr, n), 0.5);
    return deviation;
}


int main()
// simple terst function
{
    const int n = 10;
    float user_array[10] = { 1,2,3,4,5,6,7,8,9,10 };
    std::cout << "Mean: " << get_mean(user_array, n) << std::endl;
    std::cout << "Variance: " << get_variance(user_array, n) << std::endl;
    std::cout << "Deviation: " << get_deviation(user_array, n) << std::endl;
    return 0;
}