CramerRuleEqSolver.java

/*
Rahim Siddiq
Apr 13 2023
Solve 2x2 linear equations
*/

import java.util.Scanner;

public class CramerRuleEqSolver
{
	public static void main(String[] args)
	{
		// Program variables 
		double a=0, b=0, c=0, d=0, e=0, f=0; 
		double x=0, y=0;
		double determinant=0;
        
		// Title of program and description of program function to user
		System.out.println(" ====================================================================");
		System.out.println(" ====================== SOLVE LINEAR EQUATIONS ======================");
		System.out.println(" ====================================================================");
		System.out.println(" Program uses Cramer's rule to solve equations with provided input");
		System.out.println(" --------------------------------------------------------------------");
		System.out.println();
		
		Scanner input = new Scanner(System.in);
        
		System.out.println(" Please enter a value for variables a, b, c, d, e, f");
		System.out.println();
        System.out.print(" Please enter a number for a, then press [Enter]: ");
        a = input.nextDouble();
        System.out.print(" Please enter a number for b, then press [Enter]: ");
        b = input.nextDouble();
        System.out.print(" Please enter a number for c, then press [Enter]: ");
        c = input.nextDouble();
        System.out.print(" Please enter a number for d, then press [Enter]: ");
        d = input.nextDouble();
        System.out.print(" Please enter a number for e, then press [Enter]: ");
        e = input.nextDouble();
        System.out.print(" Please enter a number for f, then press [Enter]: ");
        f = input.nextDouble();
        
        // Compute the determinant of the coefficients
        determinant = a * d - b * c;

        // If the determinant is zero, the equation has no solution
        if (determinant == 0)
        {
            System.out.println(" --------------------------------------------------------------------");
            System.out.println(" The equation has no solution");
        } 
        else 
        {
            // Compute the values of x and y using Cramer's rule and display result
        	// Calculations
            x = (e * d - b * f) / determinant;
            y = (a * f - e * c) / determinant;
            // Output
            System.out.println(" --------------------------------------------------------------------");
            System.out.println(" x is: " + x + " and y is: " + y);
        }
        input.close();
    }
}