Code.org-Final-Projects/Unit-4/Complex.java

// This code is from https://algs4.cs.princeton.edu/code/edu/princeton/cs/algs4/Complex.java
// I did not write this.






/******************************************************************************
 *  Compilation:  javac Complex.java
 *  Execution:    java Complex
 *
 *  Data type for complex numbers.
 *
 *  The data type is "immutable" so once you create and initialize
 *  a Complex object, you cannot change it. The "final" keyword
 *  when declaring re and im enforces this rule, making it a
 *  compile-time error to change the .re or .im instance variables after
 *  they've been initialized.
 *
 *  % java Complex
 *  a            = 5.0 + 6.0i
 *  b            = -3.0 + 4.0i
 *  Re(a)        = 5.0
 *  Im(a)        = 6.0
 *  b + a        = 2.0 + 10.0i
 *  a - b        = 8.0 + 2.0i
 *  a * b        = -39.0 + 2.0i
 *  b * a        = -39.0 + 2.0i
 *  a / b        = 0.36 - 1.52i
 *  (a / b) * b  = 5.0 + 6.0i
 *  conj(a)      = 5.0 - 6.0i
 *  |a|          = 7.810249675906654
 *  tan(a)       = -6.685231390246571E-6 + 1.0000103108981198i
 *
 ******************************************************************************/

 public class Complex {
  private final double re;   // the real part
  private final double im;   // the imaginary part

  // create a new object with the given real and imaginary parts
  public Complex(double real, double imag) {
      re = real;
      im = imag;
  }

  // return a string representation of the invoking Complex object
  public String toString() {
      if (im == 0) return re + "";
      if (re == 0) return im + "i";
      if (im <  0) return re + " - " + (-im) + "i";
      return re + " + " + im + "i";
  }

  // return abs/modulus/magnitude
  public double abs() {
      return Math.hypot(re, im);
  }

  // return angle/phase/argument, normalized to be between -pi and pi
  public double phase() {
      return Math.atan2(im, re);
  }

  // return a new Complex object whose value is (this + b)
  public Complex plus(Complex b) {
      Complex a = this;             // invoking object
      double real = a.re + b.re;
      double imag = a.im + b.im;
      return new Complex(real, imag);
  }

  // return a new Complex object whose value is (this - b)
  public Complex minus(Complex b) {
      Complex a = this;
      double real = a.re - b.re;
      double imag = a.im - b.im;
      return new Complex(real, imag);
  }

  // return a new Complex object whose value is (this * b)
  public Complex times(Complex b) {
      Complex a = this;
      double real = a.re * b.re - a.im * b.im;
      double imag = a.re * b.im + a.im * b.re;
      return new Complex(real, imag);
  }

  // return a new object whose value is (this * alpha)
  public Complex scale(double alpha) {
      return new Complex(alpha * re, alpha * im);
  }

  // return a new Complex object whose value is the conjugate of this
  public Complex conjugate() {
      return new Complex(re, -im);
  }

  // return a new Complex object whose value is the reciprocal of this
  public Complex reciprocal() {
      double scale = re*re + im*im;
      return new Complex(re / scale, -im / scale);
  }

  // return the real or imaginary part
  public double re() { return re; }
  public double im() { return im; }

  // return a / b
  public Complex divides(Complex b) {
      Complex a = this;
      return a.times(b.reciprocal());
  }

  // return a new Complex object whose value is the complex exponential of this
  public Complex exp() {
      return new Complex(Math.exp(re) * Math.cos(im), Math.exp(re) * Math.sin(im));
  }

  // return a new Complex object whose value is the complex sine of this
  public Complex sin() {
      return new Complex(Math.sin(re) * Math.cosh(im), Math.cos(re) * Math.sinh(im));
  }

  // return a new Complex object whose value is the complex cosine of this
  public Complex cos() {
      return new Complex(Math.cos(re) * Math.cosh(im), -Math.sin(re) * Math.sinh(im));
  }

  // return a new Complex object whose value is the complex tangent of this
  public Complex tan() {
      return sin().divides(cos());
  }



  // a static version of plus
  public static Complex plus(Complex a, Complex b) {
      double real = a.re + b.re;
      double imag = a.im + b.im;
      Complex sum = new Complex(real, imag);
      return sum;
  }

  // See Section 3.3.
  public boolean equals(Object x) {
      if (x == null) return false;
      if (this.getClass() != x.getClass()) return false;
      Complex that = (Complex) x;
      return (this.re == that.re) && (this.im == that.im);
  }
}