using System;

public class Program

{

        public static void Main(string[] args)

        {

            //welcome message 

            Console.WriteLine("Welcome to the COVid OVERALL DEATHS Calculator per Month");

            //declaring the variables 

            double month, forecast;

            double error_cuadrado_total, error_cuadrado_total_viejo,

                variable_criterio = 0.0001;

            double pivote, factor;

            double[] r = new double[12];

            double[,] jacobiana = new double[12, 2];

            //Set the matrix size

            double[,] matriz = { { 0, 0, 0, 0, 0 },

                               { 0, 0, 0, 0, 0 },

                               { 0, 0, 0, 0, 0 },

                               { 0, 0, 0, 0, 0 } };

​

            //setting months and temperature

            double[] deaths= {1830, 8071, 17839, 18919, 17726, 13232, 14107, 14187, 13804, 31343, 27052, 17512};

            double[] mes = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 };

​

            //Initial values 

            Console.WriteLine("\n\nPlease introduce a Month from 1 (April-2020) to 15 (June-2021):");

            month= double.Parse(Console.ReadLine());

            Console.WriteLine("\n\nPlease introduce an aproximate forecast quantity of DEATHS from set month, according to your knowledge:");

            forecast= double.Parse(Console.ReadLine());

            double[] x = {month, forecast};

​

            error_cuadrado_total_viejo = variable_criterio * 2;

            error_cuadrado_total = 0;

//set instructions with while

            while (Math.Abs(error_cuadrado_total - error_cuadrado_total_viejo)

                > variable_criterio)

            {

                error_cuadrado_total_viejo = error_cuadrado_total;

                error_cuadrado_total = 0;

//integrate the for cycle 

                for (int i = 0; i < 12; i = i + 1)

                {

                    r[i] = x[0] * 1407 + 7153 - x[1];

                    error_cuadrado_total = error_cuadrado_total + r[i] * r[i];

​

                    jacobiana[i, 0] = 1;

                    jacobiana[i, 1] = 1;

                }

             //matrix multiplication 

                for (int i = 0; i < 2; i = i + 1)

                    for (int j = 0; j < 2; j = j + 1)

                        for (int k = 0; k < 12; k = k + 1)

                            matriz[i, j]

                                = matriz[i, j] + jacobiana[k, i] * jacobiana[k, j];

​

                for (int i = 0; i < 2; i = i + 1)

                    for (int j = 0; j < 1; j = j + 1)

                        for (int k = 0; k < 12; k = k + 1)

                            matriz[i, 2] = matriz[i, 2] - r[k] * jacobiana[k, i];

​

                //gauss elimination method 

                for (int reng = 0; reng < 2; reng = reng + 1)

                {

                    pivote = matriz[reng, reng];

                    for (int colu = 0; colu < 3; colu = colu + 1)

                        matriz[reng, colu] = matriz[reng, colu] / pivote;

                    for (int reng_elimi = 0; reng_elimi < 2; reng_elimi = reng_elimi + 1)

                        if (reng_elimi != reng)

                        {

                            factor = matriz[reng_elimi, reng];

                            for (int colu_elimi = 0; colu_elimi < 3;

                                colu_elimi = colu_elimi + 1)

                                matriz[reng_elimi, colu_elimi]

                                    = matriz[reng_elimi, colu_elimi]

                                    - factor * matriz[reng, colu_elimi];

                        }

                }

​

                //Setting values for the variables 

                Console.WriteLine("\n\nAccording to the tendency from the accumulated data of cases, in the Month "+x[0]+" there were or will be approximately "+x[1]+" sumed DEATHS.");

                Console.WriteLine("Set Forecast has a Quadratic Error of "+error_cuadrado_total+".");

                Console.WriteLine("\n\nIf the Error is bigger than 0, try a closer forecast, in order to reach the precise quantity of DEATHS for the given Month.");

            }

​

            Console.WriteLine();

        }

}

​