**复数**

数据：实部 虚部

ComplexNum类，私有(private)变量，用getter和setter访问与修改，用toString函数转为字符串

有参构造函数，传入实部和虚部创建复数ComplexNumber对象。

无参构造函数，创建复数0+0i，通过调用有参构造函数创建。

成员函数：模长，共轭，开方，加减乘除

类函数：加减乘除

成员函数需要通过ComplexNumber对象来调用，表示得到某个复数的模长、共轭、开方值，或者这个复数对象加上另一个复数得到的值，没有返回值，是对自身的修改。

类函数由static关键字修饰，则可以直接调用，或者在另一个类中通过ComplexNumber类名就可以调用，表示两个复数相加的值，返回值就是ComplexNumber对象，表示运算结果。

(类函数又叫静态函数，不能调用类中的其他成员变量和函数，只能调用类变量和类函数)

(成员函数可以调用类中的其他函数，也可以调用类函数)

代码：

packagecomplexNumber;public classComplexNumber {//成员变量

private doublerealPart;private doubleimaginaryPart;publicComplexNumber() {//TODO Auto-generated constructor stub

this(0,0);

}public ComplexNumber(double real, doubleimaginary) {this.realPart =real;this.imaginaryPart =imaginary;

}public voidadd(ComplexNumber number) {this.realPart +=number.realPart;this.imaginaryPart +=number.imaginaryPart;

}public staticComplexNumber add(ComplexNumber number1, ComplexNumber number2) {double real = number1.realPart +number2.realPart;double imag = number1.imaginaryPart +number2.imaginaryPart;return newComplexNumber(real, imag);

}public voidsubtract(ComplexNumber number) {this.realPart -=number.realPart;this.imaginaryPart -=number.imaginaryPart;

}public staticComplexNumber subtract(ComplexNumber number1, ComplexNumber number2) {double real = number1.realPart -number2.realPart;double imag = number1.imaginaryPart -number2.imaginaryPart;return newComplexNumber(real, imag);

}//(a+bi)*(c+di) = (ac-bd) + (bc+ad)i

public voidmultiply(ComplexNumber number) {this.realPart = this.realPart * number.realPart - this.imaginaryPart *number.imaginaryPart;this.imaginaryPart = this.imaginaryPart * number.realPart + this.realPart *number.imaginaryPart;

}public staticComplexNumber multiply(ComplexNumber number1, ComplexNumber number2) {double real = number1.realPart * number2.realPart - number1.imaginaryPart *number2.imaginaryPart;double imag = number1.imaginaryPart * number2.realPart - number1.realPart *number2.imaginaryPart;return newComplexNumber(real, imag);

}public voiddivide(ComplexNumber number) {//分母

double denominator =number.magnitude();this.realPart = this.realPart * number.realPart + this.imaginaryPart *number.imaginaryPart;this.realPart /=denominator;this.imaginaryPart = (this.imaginaryPart * number.realPart - this.realPart *number.imaginaryPart);this.imaginaryPart /=denominator;

}public staticComplexNumber divide(ComplexNumber number1, ComplexNumber number2) {double denominator =number2.magnitude();double real = number1.realPart * number2.realPart + number1.imaginaryPart *number2.imaginaryPart;double imag = (number1.imaginaryPart * number2.realPart - number1.realPart *number2.imaginaryPart);return new ComplexNumber(real / denominator, imag /denominator);

}public doublemagnitude() {return Math.sqrt(this.realPart*this.realPart + this.imaginaryPart*this.imaginaryPart);

}publicComplexNumber conjugate() {return new ComplexNumber(this.realPart, - this.imaginaryPart);

}public doublegetRealPart() {returnrealPart;

}public void setRealPart(doublerealPart) {this.realPart =realPart;

}public doublegetImaginaryPart() {returnimaginaryPart;

}public void setImaginaryPart(doubleimaginaryPart) {this.imaginaryPart =imaginaryPart;

}

@OverridepublicString toString() {if(this.imaginaryPart < 0)return "ComplexNumber " + realPart + "i" +imaginaryPart;return "ComplexNumber " + realPart + "i + " +imaginaryPart;

}

// 主函数，测试一下这个类public static voidmain(String[] args) {

ComplexNumber num1= new ComplexNumber(3, 4);

ComplexNumber num2= new ComplexNumber(5, 12);

System.out.println("num1 : " +num1.toString());

System.out.println("num1的模长为："+num1.magnitude());

System.out.println("num1的共轭为："+num1.conjugate());

ComplexNumber num3=ComplexNumber.add(num1, num2);

System.out.println("num3 = num1 + num2 = " +num3.toString());

num1.add(num2);

System.out.println("num1

ComplexNumber num4=ComplexNumber.subtract(num1, num2);

System.out.println("num4 = num1 - num2 = " +num4.toString());

System.out.println("num2 : " +num2.toString());

System.out.println("num2的模长为："+num2.magnitude());

System.out.println("num2的共轭为："+num2.conjugate());

}

}

运行结果：

num1 : ComplexNumber 3.0i + 4.0

num1的模长为：5.0

num1的共轭为：ComplexNumber 3.0i-4.0

num3 = num1 + num2 = ComplexNumber 8.0i + 16.0

num1

num4 = num1 - num2 = ComplexNumber 3.0i + 4.0

num2 : ComplexNumber 5.0i + 12.0

num2的模长为：13.0

num2的共轭为：ComplexNumber 5.0i-12.0