created Math which can create regressions and PolynomialFunction to

represent the regressions

CMakeLists.txt

@@ -13,4 +13,6 @@ add_executable(${PROJECT_NAME} src/main.cpp src/main.h
 		src/data/dateMoney.cpp src/data/dateMoney.h
 		src/optHandlers/optHandler.cpp src/optHandlers/optHandler.h
 		src/optHandlers/accountOptHandler.cpp src/optHandlers/accountOptHandler.h
-		src/optHandlers/mainOptHandler.cpp src/optHandlers/mainOptHandler.h)
+		src/optHandlers/mainOptHandler.cpp src/optHandlers/mainOptHandler.h
+		utilities/math.cpp utilities/math.h
+		utilities/polynomialFunction.cpp utilities/polynomialFunction.h)

src/data/accountData.cpp

@@ -96,6 +96,4 @@ Account *AccountData::getAccount() {
 	return &account;
 }
 
-AccountData::AccountData() : Data("/dev/null") {
-
-}
+AccountData::AccountData() : Data("/dev/null") {}

src/main.cpp

@@ -6,6 +6,7 @@
 #include "data/accountData.h"
 #include "optHandlers/accountOptHandler.h"
 #include "optHandlers/mainOptHandler.h"
+#include "../utilities/math.h"
 
 #include <pwd.h>
 #include <unistd.h>

utilities/math.cpp

@@ -0,0 +1,97 @@
+//
+// Created by quentin on 9/13/22.
+//
+
+#include "math.h"
+
+//Polynomial Fit
+#include <iostream>
+#include <cmath>
+
+using namespace Budget::Utilities;
+
+PolynomialFunction Math::polynomialFit(int degree, int numberOfPoints, const double x[], const double y[]) {
+	//Array that will store the values of sigma(xi),sigma(xi^2),sigma(xi^3)....sigma(xi^2numberOfPoints)
+	double X[2 * degree + 1];
+	for (int i = 0; i < 2 * degree + 1; i++) {
+		X[i] = 0;
+		for (int j = 0; j < numberOfPoints; j++) {
+			//consecutive positions of the array will store numberOfPoints,sigma(xi),sigma(xi^2),sigma(xi^3)....sigma(xi^2n)
+			X[i] = X[i] + pow(x[j], i);
+		}
+	}
+	//B is the Normal matrix(augmented) that will store the equations, 'a' is for value of the final coefficients
+	double B[degree + 1][degree + 2], a[degree + 1];
+	for (int i = 0; i <= degree; i++) {
+		for (int j = 0; j <= degree; j++) {
+			//Build the Normal matrix by storing the corresponding coefficients at the right positions except the last column of the matrix
+			B[i][j] = X[i + j];
+		}
+	}
+	
+	//Array to store the values of sigma(yi),sigma(xi*yi),sigma(xi^2*yi)...sigma(xi^degree*yi)
+	double Y[degree + 1];
+	for (int i = 0; i < degree + 1; i++) {
+		Y[i] = 0;
+		for (int j = 0; j < numberOfPoints; j++) {
+			//consecutive positions will store sigma(yi),sigma(xi*yi),sigma(xi^2*yi)...sigma(xi^degree*yi)
+			Y[i] = Y[i] + pow(x[j], i) * y[j];
+		}
+	}
+	for (int i = 0; i <= degree; i++) {
+		//load the values of Y as the last column of B(Normal Matrix but augmented)
+		B[i][degree + 1] = Y[i];
+	}
+	
+	//degree is made degree+1 because the Gaussian Elimination part below was for degree equations, but here degree is the degree of polynomial and for degree degree we get degree+1 equations
+	degree = degree + 1;
+	//From now Gaussian Elimination starts(can be ignored) to solve the set of linear equations (Pivotisation)
+	for (int i = 0; i < degree; i++) {
+		for (int k = i + 1; k < degree; k++) {
+			if (B[i][i] < B[k][i]) {
+				for (int j = 0; j <= degree; j++) {
+					double temp = B[i][j];
+					B[i][j] = B[k][j];
+					B[k][j] = temp;
+				}
+			}
+		}
+	}
+	
+	//loop to perform the gauss elimination
+	for (int i = 0; i < degree - 1; i++) {
+		for (int k = i + 1; k < degree; k++) {
+			double t = B[k][i] / B[i][i];
+			for (int j = 0; j <= degree; j++) {
+				//make the elements below the pivot elements equal to zero or elimnate the variables
+				B[k][j] = B[k][j] - t * B[i][j];
+			}
+		}
+	}
+	
+	//back-substitution
+	for (int i = degree - 1; i >= 0; i--) {
+		//x is an array whose values correspond to the values of x,y,z..
+		//make the variable to be calculated equal to the rhs of the last equation
+		a[i] = B[i][degree];
+		for (int j = 0; j < degree; j++) {
+			//then subtract all the lhs values except the coefficient of the variable whose value is being calculated
+			if (j != i) {
+				a[i] = a[i] - B[i][j] * a[j];
+			}
+		}
+		//now finally divide the rhs by the coefficient of the variable to be calculated
+		a[i] = a[i] / B[i][i];
+	}
+	std::cout << "\nThe values of the coefficients are as follows:\n";
+	for (int i = 0; i < degree; i++)
+		std::cout << "x^" << i << "=" << a[i] << std::endl;            // Print the values of x^0,x^1,x^2,x^3,....
+	std::cout << "\nHence the fitted Polynomial is given by:\ny=";
+	for (int i = 0; i < degree; i++)
+		std::cout << " + (" << a[i] << ")" << "x^" << i;
+	std::cout << "\n";
+	
+	std::vector<double> va(a, a + degree);
+	return PolynomialFunction(va);
+}
+

utilities/math.h

@@ -0,0 +1,19 @@
+//
+// Created by quentin on 9/13/22.
+//
+
+#ifndef BUDGET_MATH_H
+#define BUDGET_MATH_H
+
+
+#include "polynomialFunction.h"
+
+namespace Budget::Utilities {
+	class Math {
+	public:
+		static PolynomialFunction polynomialFit(int degree, int numberOfPoints, const double x[], const double y[]);
+	};
+}
+
+
+#endif //BUDGET_MATH_H

utilities/polynomialFunction.cpp

@@ -0,0 +1,21 @@
+//
+// Created by quentin on 9/13/22.
+//
+
+#include "polynomialFunction.h"
+
+#include <utility>
+#include <cmath>
+
+using namespace Budget::Utilities;
+
+PolynomialFunction::PolynomialFunction(std::vector<double> a) : a(std::move(a)) {}
+
+double PolynomialFunction::get(double x) {
+	double ret = 0;
+	for (int i = 0; i < a.size(); ++i) {
+		ret += a[i] * std::pow(x, i);
+	}
+	
+	return ret;
+}

utilities/polynomialFunction.h

@@ -0,0 +1,25 @@
+//
+// Created by quentin on 9/13/22.
+//
+
+#ifndef BUDGET_POLYNOMIALFUNCTION_H
+#define BUDGET_POLYNOMIALFUNCTION_H
+
+
+#include <vector>
+
+namespace Budget::Utilities {
+	class PolynomialFunction {
+	private:
+	public:
+		explicit PolynomialFunction(std::vector<double> a);
+		
+		double get(double x);
+	
+	private:
+		std::vector<double> a;
+	};
+}
+
+
+#endif //BUDGET_POLYNOMIALFUNCTION_H