import java.util.Scanner;

public class CalculatorDemo {
  public static void main(String[] args){
    Scanner console = new Scanner(System.in);
    String more = "no";
    do {
      System.out.println("Enter a number: ");
      System.out.print("x: ");
      double x = console.nextDouble();
      console.nextLine(); // read past the carriage return
      System.out.println("Now enter an operator to apply to that number");
      System.out.println("you can choose from sin, cos, tan, exp, log, sqrt");
      System.out.print("operator: ");
      String op = console.nextLine().trim(); // remove the spaces before and after the answer!
      double result;
      switch (op){
      case "sin": result=Math.sin(x); break;
      case "cos": result=Math.cos(x); break;
      case "tan": result=Math.tan(x); break;
      case "exp": result=Math.exp(x); break;
      case "log": result=Math.log(x); break;
      case "sqrt": result=Math.sqrt(x); break;
      default: result=0;
    }
      // you write the code to calculate the result of applying the operator to x


      System.out.printf("%s(%f)=%f%n",op,x,result);
      System.out.print("Another? (yes or no): ");
      more = console.nextLine().trim();
    } while (more.equals("yes"));
    System.out.println("Goodbye");
  }
}