complex.java

一个一元曲线多项式数值演示例子

package numbercruncher.mathutils;

/**
 * Perform basic complex arithmetic.  The complex objects are
 * immutable, and complex operations create new complex objects.
 */
public class Complex {
  /** the real part */
  private float real;
  /** the imaginary part */
  private float imaginary;

  /**
   * Constructor.
   * @param real the real part
   * @param imaginary the imaginary part
   */
  public Complex(float real, float imaginary) {
    this.real = real;
    this.imaginary = imaginary;
  }

  /**
   * Return this complex number's real part.
   * @return the real part
   */
  public float real() {
    return real;
  }

  /**
   * Return this complex number's imaginary part.
   * @return the imaginary part
   */
  public float imaginary() {
    return imaginary;
  }

  /**
   * Compute this complex number's modulus
   */
  public float modulus() {
    return (float) Math.sqrt(real * real + imaginary * imaginary);
  }

  /**
   * Return whether or not this complex number
   * is equal to another one.
   * @param z the other complex number
   * @return true if equal, false if not
   */
  public boolean equal(Complex z) {
    return (real == z.real()) && (imaginary == z.imaginary());
  }

  /**
   * Add another complex number to this one.
   * @param a the other complex number
   * @return a new complex number that is the sum
   */
  public Complex add(Complex z) {
    return new Complex(real + z.real(),
                       imaginary + z.imaginary());
  }

  /**
   * Subtract another complex number from this one.
   * @param a the other complex number
   * @return a new complex number that is the difference
   */
  public Complex subtract(Complex z) {
    return new Complex(real - z.real(),
                       imaginary - z.imaginary());
  }

  /**
   * Multiply this complex number by another one.
   * @param a the other complex number
   * @return a new complex number that is the product
   */
  public Complex multiply(Complex z) {
    return new Complex(real * z.real() - imaginary * z.imaginary(),
                       real * z.imaginary() + imaginary * z.real());
  }

  /**
   * Divide this complex number by another one.
   * @param a the other complex number
   * @return a new complex number that is the quotient
   */
  public Complex divide(Complex z) {
    float denom = z.real() * z.real() + z.imaginary() * z.imaginary();
    float qr = (real * z.real() + imaginary * z.imaginary()) / denom;
    float qi = (imaginary * z.real() - real * z.imaginary()) / denom;

    return new Complex(qr, qi);
  }

  /**
   * Return the string representation of this complex number.
   * @return the string representation
   */
  public String toString() {
    String operator = (imaginary >= 0) ? "+" : "-";
    return real + operator + Math.abs(imaginary) + "i";
  }
}