I was wondering if anyone was able to understand the reason why this program doesn't return NaN the way it should.
I'm currently writing a program that calculates the solutions of a quadratic equation, but if the solutions are not real, I want it to print out "The solutions are not real" instead of NaN. Instead, it keeps on printing NaN nonetheless.
This is the code I've written:
import java.util.Scanner;
import java.lang.*;
public class QuadraticEquationTester {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Insert the value a of the following equation: a*x^(2)+b*x+c=0");
double a = Double.parseDouble(scan.nextLine());
System.out.println("Insert the value b of the following equation: a*x^(2)+b*x+c=0");
double b = Double.parseDouble(scan.nextLine());
System.out.println("Insert the value c of the following equation: a*x^(2)+b*x+c=0");
double c = Double.parseDouble(scan.nextLine());
scan.close();
QuadraticEquation equation1 = new QuadraticEquation(a, b, c);
equation1.getEquation();
System.out.println("Does this equation has solutions? " + equation1.hasSolutions());
System.out.println("How many solutions does this equation have? " + equation1.howManySolutions());
if (equation1.getSolution1() == Double.NaN && equation1.getSolution2() == Double.NaN) {
System.out.println("There are no real solutions");
}
if (equation1.getSolution1() != Double.NaN) {
System.out.println("The first solution is: " + equation1.getSolution1());
} else if (equation1.getSolution1() == Double.NaN) {
System.out.println("The first solution is not real");
}
if (equation1.getSolution2() != Double.NaN) {
System.out.println("The second solution is: " + equation1.getSolution2());
} else if (equation1.getSolution2() == Double.NaN) {
System.out.println("The second solution is not real");
}
if (equation1.getSolution1() != Double.NaN && equation1.getSolution2() != Double.NaN) {
System.out.println(equation1.getAllSolutions());
}
}
}
class QuadraticEquation {
// I'm initialing the variables
private double a;
private double b;
private double c;
private double delta;
// This is the basic constructor: it initializes the variables to zero
public QuadraticEquation() {
this.a = 0;
this.b = 0;
this.c = 0;
}
public QuadraticEquation(double aCoefficient, double bCoefficient, double cCoefficient) {
this.a = aCoefficient;
this.b = bCoefficient;
this.c = cCoefficient;
this.delta = (Math.pow(this.b, 2)) - 4 * this.a * this.c;
}
public void getEquation() {
System.out
.println("The equation we're going to solve is " + this.a + "*x^(2)+" + this.b + "*x+" + this.c + "=0");
}
public double getSolution1() {
double solution1 = (-this.b + (Math.sqrt(this.delta))) / (2 * this.a);
return solution1;
}
public double getSolution2() {
double solution2 = (-this.b - (Math.sqrt(this.delta))) / (2 * this.a);
return solution2;
}
public String getAllSolutions() {
double solution1 = (-this.b + (Math.sqrt(this.delta))) / (2 * this.a);
double solution2 = (-this.b - (Math.sqrt(this.delta))) / (2 * this.a);
return "The first solution is: " + solution1 + " while the second solution is: " + solution2;
}
public boolean hasSolutions() {
if (this.delta >= 0) {
return true;
} else if (this.delta < 0) {
return false;
}
return false;
}
public String howManySolutions() {
if (this.a == 0 && this.b == 0 && this.c != 0) {
return "0 Solutions";
} else if (this.a == 0 && this.b != 0) {
return "1 Solution";
} else if (this.a == 0 && this.b == 0 && this.c == 0) {
return "Infinite Solutions";
} else {
return "2 Solutions";
}
}
public static boolean isNaN(double v) {
if (v == Double.NaN) {
return true;
}
else return false;
}
}
