创建一个名为Complex的类，进行复数的运算。Complex需要具有的功能： 提供一个构造函数，它使这个类的对象在声明时得以初始化； 提供一个拷贝构造函数用来创建对象； 两个Complex的加法；实部相加，虚部相加； 两个Complex值相减：实部相减，虚部相减 两个Complex值相乘 以(a + b * i)的形式打印Complex的值，其中a为实部，b为虚部。

FFTW is a free collection of fast C routines for computing the Discrete Fourier Transform in one or more dimensions. It includes complex, real, symmetric, and parallel transforms, and can handle arbitrary array sizes efficiently. FFTW is typical

s变换和反变换程序，Reference is "Localization of the Complex Spectrum: The S Transform" % from IEEE Transactions on Signal Processing, vol. 44., number 4, April 1996, pages 998-1001.