#include?
#include?
#include?
#include?
#include?
#include?
using?namespace?std;

#define?????pi?????（（double）3.1415926）

struct?DESIGN_SPECIFICATION
{
????double?Passband;???
????double?Stopband;
	double?Passband_attenuation;
????double?Stopband_attenuation;
};

//復(fù)數(shù)乘
_complex?ComplexMul（?_complex?a?_complex?b?）
{
	_complex?c;
	c.x?=?a.x*b.x?-?a.y*b.y;
	c.y?=?a.y*b.x?+?a.x*b.y;
	return?c;
}

//復(fù)數(shù)除
_complex?ComplexDiv（?_complex?a?_complex?b）
{
	_complex?c;
	double?dTmp?=?b.x?*?b.x?+?b.y?*?b.y;
	//除數(shù)太小防溢出
	if（?dTmp?		c.x?=?1.0E300;
		c.y?=?1.0E300;
		return?c;
	}
	c.x?=?（?a.x?*?b.x?+?a.y?*?b.y）?/?dTmp;
	c.y?=?（?a.x?*?b.y?-?a.y?*?b.x）?/?dTmp;
	return?c;?
}

//計(jì)算濾波器階數(shù)N
int?Buttord（double?Passband
	????????double?Stopband
			double?Passband_attenuation
	????????double?Stopband_attenuation）
{
???int?N;

???printf（“Wp?=??%lf??[rad/sec]?\n“?Passband）;
???printf（“Ws?=??%lf??[rad/sec]?\n“?Stopband）;
???printf（“Ap?=??%lf??[dB]?\n“?Passband_attenuation）;
???printf（“As?=??%lf??[dB]?\n“?Stopband_attenuation）;
???printf（“--------------------------------------------------------\n“?）;
	?
???N?=?ceil（0.5*（?log10?（（?pow?（10?Stopband_attenuation/10）?-?1）/
	???（?pow?（10?Passband_attenuation/10）?-?1））?/?log10?（Stopband/Passband）?））;
????
???return?（int）N;
}

//計(jì)算S平面的濾波器系數(shù)
int?Butter（int?N?double?Cutoff?double?*a?double?*b）
{
????double?dk?=?0;
????int?k?=?0;
????int?count?=?0count_1?=?0;

????_complex?*poles?*Res?*Res_Save;
	poles?=?new?_complex[N]（）;
????Res???=?new?_complex[N+1]（）;
	Res_Save?=?new?_complex[N+1]（）;
	memset（poles?0?sizeof（_complex）*（N））;
	memset（Res?0?sizeof（_complex）*（N+1））;
	memset（Res_Save?0?sizeof（_complex）*（N+1））;

????if（（N?%?2）?==?0）?dk?=?0.5;
????else?dk?=?0;

????for（k?=?0;k?<=?（（2*N）-1）?;?k++）
????{
		if（Cutoff*cos（（2*k+N-1）*（pi/（2*N）））??????????{	???
????????????poles[count].x?=?-Cutoff*cos（（2*k+N-1）*（pi/（2*N）））;
			poles[count].y?=?-Cutoff*sin（（2*k+N-1）*（pi/（2*N）））;	??
			?count++;
	????????if?（count?==?N）?break;
?????????}
????}?

?????printf（“Pk?=???\n“?）;??
	?
?????for（count?=?0;?count??????{
???????????printf（“（%lf）?+?（%lf?i）?\n“??-poles[count].x?-poles[count].y）;
?????}

?????printf（“--------------------------------------------------------\n“?）;
	?
?????Res[0].x?=?poles[0].x;?
?????Res[0].y?=?poles[0].y;

?????Res[1].x?=?1;?
?????Res[1].y=?0;

????for（count_1?=?0;count_1?????{
	?????for（count?=?0;count?<=?count_1?+?2;count++）
	?????{
	??????????if（0?==?count）
			??{
?	??????????????Res_Save[count]?=?ComplexMul（?Res[count]?poles[count_1+1]?）;??
			??}

	??????????else?if（（count_1?+?2）?==?count）
	??????????{
	????????????????Res_Save[count].x?+=?Res[count?-?1].x;
					Res_Save[count].y?+=?Res[count?-?1].y;	
	??????????}		??
		????else?
		????{
				Res_Save[count]?=?Comple

?屬性????????????大小?????日期????時(shí)間???名稱(chēng)
-----------?---------??----------?-----??----
?????目錄???????????0??2017-04-27?15:55??Butterworth\
?????文件???????48322??2017-04-06?09:27??Butterworth\1.txt
?????文件??????145792??2017-03-27?19:25??Butterworth\123.txt
?????文件??????149793??2017-04-01?15:24??Butterworth\1234.txt
?????文件??????106912??2017-05-01?10:16??Butterworth\butter1.txt
?????文件????????4335??2017-04-06?21:29??Butterworth\Butterworth.dsp
?????文件?????????530??2017-04-04?19:34??Butterworth\Butterworth.dsw
?????文件???????41984??2017-05-01?10:16??Butterworth\Butterworth.ncb
?????文件???????53760??2017-05-01?10:16??Butterworth\Butterworth.opt
?????文件????????1165??2017-05-01?10:16??Butterworth\Butterworth.plg
?????目錄???????????0??2017-04-27?15:55??Butterworth\Debug\
?????文件??????254976??2017-05-01?10:16??Butterworth\Debug\Butterworth.bsc
?????文件??????315455??2017-05-01?10:16??Butterworth\Debug\Butterworth.exe
?????文件??????418012??2017-05-01?10:16??Butterworth\Debug\Butterworth.ilk
?????文件?????2095684??2017-05-01?10:10??Butterworth\Debug\Butterworth.pch
?????文件?????1131520??2017-05-01?10:16??Butterworth\Debug\Butterworth.pdb
?????文件???????28267??2017-05-01?10:16??Butterworth\Debug\main.obj
?????文件???????????0??2017-05-01?10:16??Butterworth\Debug\main.sbr
?????文件??????123904??2017-05-01?10:16??Butterworth\Debug\vc60.idb
?????文件??????110592??2017-05-01?10:16??Butterworth\Debug\vc60.pdb
?????文件???????10932??2017-05-01?10:16??Butterworth\main.cpp
?????文件??????106912??2017-04-06?09:28??Butterworth\output22.txt