/**
 * A record type for representing complex numbers, where
 * a complex number consists of two real numbers called its
 * real and imaginary parts.  The class includes methods for
 * doing arithmetic with complex numbers.
 */
public record Complex(double re, double im)  {
    
    // Some named constants for common complex numbers.

    public final static Complex ONE = new Complex(1,0);
    public final static Complex ZERO = new Complex(0,0);
    public final static Complex I = new Complex(0,1);

    /**
     * This constructor creates a complex number with a given
     * real part and with imaginary part zero.
     */
    public Complex(double re) {
        this(re,0);
    }
    
    /**
     * Creates string representations of complex number such
     * as:  3.0 + I*5.0,  -I*3.14,   2.7 - I*8.6,   3.14
     */
    public String toString() {
        if (im == 0)
            return String.valueOf(re);
        else if (re == 0) {
            if (im < 0)
                return "-I*" + (-im);
            else
                return "I*" + im;
        }
        else if (im < 0)
            return re + " - " + "I*" + (-im);
        else
            return re + " + " + "I*" + im;
    }

    // Some methods for doing arithmetic on two complex numbers
    
    public Complex plus(Complex c) {
        return new Complex(re + c.re, im + c.im);
    }
    public Complex minus(Complex c) {
        return new Complex(re - c.re, im - c.im);
    }
    public Complex times(Complex c) {
        return new Complex(re*c.re - im*c.im,
                re*c.im + im*c.re);
    }
    public Complex dividedBy(Complex c) {
        double denom = c.re*c.re + c.im*c.im;
        double real = (re*c.re + im*c.im)/denom;
        double imaginary = (im*c.re - re*c.im)/denom;
        return new Complex(real,imaginary);
    }
        
} // end record Complex