import java.text.DecimalFormat;

/* An instance of this class represents a complex number.  There are 
** mutator methods --corresponding to the four core arithmetic operators--
** by which an instance of the class can be modified.
** 
** Authors: R. McCloskey and < STUDENT's NAME >
** Date: Feb. 2022
** Collaborators: ...
** Known Defects: ...
*/
public class ComplexNumber {

   // instance variables
   // ------------------

   private double realPart;  // Stores the "real" part of this complex number
   private double imagPart;  // Stores the "imaginary" part


   // constructors
   // ------------

   /* Establishes this complex number as being a + bi.
   */
   public ComplexNumber(double a, double b) {
      // STUB
   }

   /* Establishes this complex number as being 0 + 0i.
   */
   public ComplexNumber() { this(0.0, 0.0); }

   /* Establishes this complex number as being identical to the given one.
   */
   public ComplexNumber(ComplexNumber c) {
      this(c.realPart, c.imagPart);
   }


   // observers
   // ---------

   /* Returns the real part of this complex number.
   */
   public double realPart() { return 0; }  // STUB

   /* Returns the imaginary part of this complex number.
   */
   public double imaginaryPart() { return 0; }  // STUB

   /* Returns a string of the form "a + bi" describing this complex number,
   ** where each of 'a' and 'b' is a real number with up to four digits after
   ** the decimal point.
   */
   public String toString() {
      final DecimalFormat df = new DecimalFormat("#.####");
      return df.format(realPart) + " + " + df.format(imagPart) + "i";
   }


   // mutators
   // --------

   /* In effect, performs the assignment this = this + other,
   ** consistent with the rule that 
   ** (a + bi) + (c + di) = (a+c) + (b+d)i.
   */
   public void addTo(ComplexNumber other) {
      realPart = realPart + other.realPart;
      imagPart = imagPart + other.imagPart;
   }

   /* In effect, performs the assignment this = this - other,
   ** consistent with the rule that 
   ** (a + bi) - (c + di) = (a-c) + (b-d)i.
   */
   public void subtractFrom(ComplexNumber other) {
      // STUB
   }

   /* In effect, performs the assignment this = this * other,
   ** consistent with the rule that 
   ** (a + bi) * (c + di) = (ac - bd) + (bc + ad)i.
   */
   public void multiplyBy(ComplexNumber other) {
      // STUB
   }

   /* In effect, performs the assignment this = this / other,
   ** consistent with the rule that 
   ** (a + bi) / (c + di) = 
   **    ((ac + bd) / (c^2 + d^2)) + ((bc - ad) / (c^2 + d^2))i.
   */
   public void divideBy(ComplexNumber other) {
      // STUB
   }

}