Trapozoidal rule in C++

Area under curve trapozoidal rule

Calculate area under curved with trapozoidal rule and implemented in C++

30 Jun 2022

mathhomeworkprogramming

Introduction

First it read the data from the CSV file. Then it put the data into arrays. After that the program calculate trapezoidal area using for-loop. Finally, it output the result. NOTE: You must convert the excel file to csv file and remove the header and store it in the same directory in order to make the program work

Data

Here is the data with x and y points

Code

/*30/06/2022 By Koungmeng*/
#include <iostream>
#include <fstream>

int main()
{
    char c; //useless variable haha
    std::fstream File("AUC_data.csv");
    double arr_x[351];
    double arr_y[351];
    double AUC = 0.0;
    //Read file from csv and put to array
    for (int i = 0; i < 351; i++)
    {
        File >> arr_x[i] >> c >> arr_y[i];
    }
    //Calculate AUC using Trapezoidal Rule
    for (int i = 0; i < 350; i++)
    {
        AUC += (arr_y[i] + arr_y[i + 1]) * (arr_x[i + 1] - arr_x[i]) / 2; //Area = (B+b)*h/2
    }
    std::cout << "The area under curve using trapezoidal rule is: " <<AUC << std::endl;
    std::cin.get();
    return 0;
}

Result