// "Java Tech"
//  Code provided with book for educational purposes only.
//  No warranty or guarantee implied.
//  This code freely available. No copyright claimed.
//  2003
//
//

/**
  * This is a kthComplex number class with the essential features
  * needed for computations. The real and imaginary
  * parts can be accessed directly for fast operation. (See
  * kthComplexImm for an immutable version of a kthComplex number
  * class.)
  *
  * Several of the common kthComplex number operations are provided
  * as static methods. New instances of kthComplex are returned
  * by the operations.
  *
 **/
public class kthComplex
{
  // Properties
  public double real;
  public double img;


  /** Constructor that initializes the real & imag values. **/
  kthComplex  (double r, double i) {
    real = r; img = i;
  }


  /** Get methods for real & imaginary parts. **/
  public double real () {
    return real;
  }

  public double img () {
    return img;
  }

  /** Define an add method. **/
  public void add (kthComplex cvalue) {
    real = real + cvalue.real;
    img  = img  + cvalue.img;
  }


  /** Define a subtract method. **/
  public void subtract (kthComplex cvalue) {
    real = real - cvalue.real;
    img  = img  - cvalue.img;
  }


  /**
    * Define a static add method that creates a
    * a new kthComplex object with the sum.
   **/
  public static kthComplex add (kthComplex cvalue1, kthComplex cvalue2) {
    double r = cvalue1.real + cvalue2.real;
    double i = cvalue1.img  + cvalue2.img;
    return new kthComplex (r,i);
  }


  /** Define a static subtract method that creates a
    * a new kthComplex object equal to
    *
    *  cvalue1 - cvalue2.
   **/
  public static kthComplex subtract (kthComplex cvalue1, kthComplex cvalue2) {
    double r = cvalue1.real - cvalue2.real;
    double i = cvalue1.img  - cvalue2.img;
    return new kthComplex (r,i);
  }


  /**
    * Check for the equality of this object with that of the argument.
   **/
  public boolean equals (kthComplex cvalue) {
    return ( (real == cvalue.real) &&
             (img  == cvalue.img) ) ;
  }

  /**
    * Provide the magnitude of the kthComplex value.
   **/
  public double modulus () {
    return Math.sqrt (real*real + img*img);
  }

  /**
    * Multiply this kthComplex object by the kthComplex argument.
   **/
  public void multiply (kthComplex cvalue) {
    double r2 = real * cvalue.real - img * cvalue.img;
    double i2 = real * cvalue.img  + img * cvalue.real;
    real = r2;
    img  = i2;
  }


  /** Define a static multiply method that creates a
    * a new kthComplex object with the product.
   **/
  public static kthComplex multiply (kthComplex cvalue1, kthComplex cvalue2) {
    double r2 = cvalue1.real * cvalue2.real -
                cvalue1.img * cvalue2.img;
    double i2 = cvalue1.img  * cvalue2.real +
                cvalue1.real  * cvalue2.img;
    return new kthComplex (r2, i2);
  }


  /**
    * Divide this kthComplex object by the kthComplex argument.
   **/
  public void divide (kthComplex cvalue) {
    double denom = cvalue.real * cvalue.real +
                   cvalue.img  * cvalue.img;

    double r = real * cvalue.real +
               img  * cvalue.img;

    double i = img  * cvalue.real -
               real * cvalue.img;

    real = r/denom;
    img  = i/denom;
  }


  /** Define a static divide method that creates a
    * a new kthComplex object with the result of
    *
    *  cvalue1/cvalue2.
   **/
  public static kthComplex divide (kthComplex cvalue1, kthComplex cvalue2) {
    double denom = cvalue2.real * cvalue2.real +
                   cvalue2.img  * cvalue2.img;

    double r = cvalue1.real * cvalue2.real +
               cvalue1.img  * cvalue2.img;

    double i = cvalue1.img * cvalue2.real -
               cvalue1.real * cvalue2.img;

    return new kthComplex (r/denom, i/denom);
  }

  /** Return a string representation of the kthComplex value. **/
  public String toString () {
    String img_sign = (img < 0) ? " - " : " + ";
    return (real +  img_sign + img + "i");
  }

} // Complex