格式 [sqnr,a_quan,code]=u_pcm(a,n)

输入样值序列a 、量化电平数目n, 程序计算量化间隔、进行均匀量化、进行编码、计算量化信噪比， 返回量化信噪比squn、编码前的量化序列a_quan、编码后的码序列code。

-Format [sqnr, a_quan, code] = u_pcm (a, n) input sample value sequence a, the number of quantization levels n, the calculation procedures to quantify interval, the uniform quantization, coding, computing quantization noise ratio, return quantization noise ratio squn, to quantify the pre-coding sequence a_quan, coding sequences after the code.