傅里叶变换的调用程序，可以实现正、逆傅里叶变换。函数返回结果为变换后的实部与虚部，用法简单。其中n为变换的点的个数，为2的幂次方，l和l0控制变换的正逆。-Fourier transform of the caller, can be achieved and inverse Fourier transform. Function returns the result of the transformed real and imaginary parts, use simple. Where n is the number of transform points, a power of 2, l and l0 control the forward and inverse transform.