Java/자바] 복소수 사칙연산 클래스; 덧셈, 뺄셈, 곱셈, 나눗셈; Complex Number Class

public class Example {
  public static void main(String[] args) {

    Complex a = new Complex(8, 3); // 복소수 8+3i
    Complex b = new Complex(5, 2); // 복소수 5+2i


    // 복소수의 덧셈
    System.out.println(Complex.add(a, b));
    // 출력 결과: 13.0+5.0i


    // 복소수의 뺄셈
    System.out.println(Complex.subtract(a, b));
    // 출력 결과: 3.0+1.0i


    // 복소수의 곱셈
    System.out.println(Complex.multiply(a, b));
    // 출력 결과: 34.0+31.0i


    // 복소수의 나눗셈
    System.out.println(Complex.divide(a, b));
    // 출력 결과: 1.5862068965517242-0.034482758620689655i




    // 복소수 a의 실수부 구하기
    System.out.println(a.getReal());
    // 출력 결과: 8.0


    // 복소수 a의 허수부 구하기
    System.out.println(a.getImaginary());
    // 출력 결과: 3.0


    // 복소수 a의 절대값/크기값(magnitude) 구하기
    System.out.println(a.magnitude());
    // 출력 결과: 8.54400374531753
    // 8+3i의 경우, 8^2 + 3^2 의 제곱근입니다.


  }
}

/** A class to represent Complex Numbers. A Complex object is
 * immutable once created; the add, subtract and multiply routines
 * return newly created Complex objects containing the results.
 *
 */

public class Complex {

  /** The real part */
  private double r;


  /** The imaginary part */
  private double i;


  /** Construct a Complex */
  Complex(double rr, double ii) {
    r = rr;
    i = ii;
  }


  /** Display the current Complex as a String, for use in
   * println( ) and elsewhere.
   */
  public String toString() {
    StringBuffer sb = new StringBuffer().append(r);

    if (i > 0)
      sb.append('+');    // else append(i) appends - sign

    return sb.append(i).append('i').toString();
  }


  /** Return just the Real part */
  public double getReal() {
    return r;
  }


  /** Return just the Imaginary part */
  public double getImaginary() {
    return i;
  }


  /** Return the magnitude of a complex number */
  public double magnitude() {
    return Math.sqrt(r*r + i*i);
  }


  /** Add another Complex to this one */
  public Complex add(Complex other) {
    return add(this, other);
  }


  /** Add two Complexes */
  public static Complex add(Complex c1, Complex c2) {
    return new Complex(c1.r+c2.r, c1.i+c2.i);
  }


  /** Subtract another Complex from this one */
  public Complex subtract(Complex other) {
    return subtract(this, other);
  }


  /** Subtract two Complexes */
  public static Complex subtract(Complex c1, Complex c2) {
    return new Complex(c1.r-c2.r, c1.i-c2.i);
  }


  /** Multiply this Complex times another one */
  public Complex multiply(Complex other) {
    return multiply(this, other);
  }


  /** Multiply two Complexes */
  public static Complex multiply(Complex c1, Complex c2) {
    return new Complex(c1.r*c2.r - c1.i*c2.i, c1.r*c2.i + c1.i*c2.r);
  }


  /** Divide c1 by  c2.
    * @author Gisbert Selke.
   */
  public static Complex divide(Complex c1, Complex c2) {
    return new Complex(
    (c1.r*c2.r+c1.i*c2.i)/(c2.r*c2.r+c2.i*c2.i),
    (c1.i*c2.r-c1.r*c2.i)/(c2.r*c2.r+c2.i*c2.i));
  }


}