Add Calculator.java

homework1/Calculator.java

+/**
+ * File:        Calculator.java
+ * Author:      Adombang Munang Mbomndih
+ * Created:     22.10.2018
+ *
+ * Description: Calculator for a polynomial fraction, with variable inputs from users
+ */
+
+package ee.taltech.homework1;
+
+import java.util.Scanner;
+
+public class Calculator
+{
+	private Scanner scanner;
+	private Double startingValue, step, lowerLimit, X, Y;
+	private int counter = 0;
+
+	/**
+	 * Main entry point of application
+	 */
+	public static void main(String[] args)
+	{
+		Calculator calculator = new Calculator();
+		
+		calculator.scanner = new Scanner(System.in);
+		calculator.getStartingValue();
+		calculator.getStep();
+		calculator.getLowerLimit();
+		
+		System.out.println("\nStarting value: "
+				+ calculator.startingValue 
+				+ " | Step: " + calculator.step 
+				+ " | Lower limit: " 
+				+ calculator.lowerLimit);
+		
+		calculator.computeY();
+		System.out.println("\nDone!");
+	}
+	
+	/**
+	 * Function to initialize the start value with user's input
+	 */
+	private void getStartingValue()
+	{
+		while (true)  // Keep asking until user inputs correct value
+		{
+			try
+			{
+				System.out.println("Enter starting value: ");
+				startingValue = Double.parseDouble(scanner.nextLine());
+				break;
+			}
+			catch (NullPointerException npe)
+			{
+				System.out.println("Starting value cannot be null!");
+			}
+			catch (NumberFormatException nfe)
+			{
+				System.out.println("Starting value must be a real number!");
+			}
+		}
+	}
+	
+	/**
+	 * Function to initialize the step with user's input
+	 */
+	private void getStep()
+	{
+		while (true)  // Keep asking until user inputs correct value
+		{
+			try
+			{
+				while (true) {
+					System.out.println("Enter step: ");
+					step = Double.parseDouble(scanner.nextLine());
+					
+					if (step > 0) break;
+					
+					System.out.println("Step must be greater than zero!");
+				}
+				break;
+			}
+			catch (NullPointerException npe)
+			{
+				System.out.println("Step cannot be null!");
+			}
+			catch (NumberFormatException nfe)
+			{
+				System.out.println("Step must be a real number!");
+			}
+		}
+	}
+	
+	/**
+	 * Function to initialize the lower limit of the function with user's input
+	 */
+	private void getLowerLimit()
+	{
+		while (true) // Keep asking until user inputs correct value
+		{
+			try
+			{
+				System.out.println("Enter lower limit: ");
+				lowerLimit = Double.parseDouble(scanner.nextLine());
+				break;
+			}
+			catch (NullPointerException npe)
+			{
+				System.out.println("Lower limit cannot be null!");
+			}
+			catch (NumberFormatException nfe)
+			{
+				System.out.println("Lower limit must be a real number!");
+			}
+		}
+	}
+	
+	/**
+	 * Function to solve the equation based on the user's inputs. Prints out result on terminal.
+	 */
+	private void computeY()
+	{
+		X = startingValue;
+		System.out.println("\nx:\ty=f(x): ");
+		do {
+			double tempFraction1 = (2 * Math.pow(X, 2)) + (3 * X) + 4;
+			double tempFraction2 = Math.pow(tempFraction1, 3) - 7;
+			
+			if (tempFraction2 == 0)
+			{
+				// cannot divide by zero
+				System.out.println(X + "\t'Not available!'");
+			}
+			else if (tempFraction2 < 0)
+			{
+				// square root of a negative number is complex
+				System.out.println(X + "\t'Complex number!'");
+			}
+			else
+			{
+				double numerator = (2 * X) + 1;
+				double denomenator = Math.sqrt(tempFraction2);
+				Y = numerator / denomenator;
+				System.out.println(X + "\t" + Y);
+			}
+			X = (++counter * step) + startingValue;
+		}
+		while (lowerLimit <= Y && counter < 15);
+	}
+
+}