西北工业大学Matlab实验报告(2016)

1、西北工业大学基于MATLA的数字信号处理实验报告学院:学号:姓名:专业:实验时间:指导教师:2016 年6月冯燕西北工业大学2016年06月实验一 MATLAB基本编程实验一、实验目的及要求1 .熟悉MATLA瓯行环境；2 .掌握MATLAB勺基本语法和函数；3 .掌握MATLAB勺基本绘图功能二、实验设备(环境)及要求4 .计算机5 . Matlab软件编程实验平台三、实验内容与步骤1 .求下列线性方程组的解6x1 3x2 4x3 = 3-2x1 5x2 7x3 - -48x1 - 4x2 - 3x3 -72 .编写一个MATLA函数文件，该函数的功能是求出最大的 n值， 使得n! <

2、 real max。通过M文件或命令行调用该函数文件计算 realmax=50000 时的 n 值。13 .某多项式的定义为：y = cos(m*cos (x)其中x的值介于-1,1之间 当m的值由1变化到5,可以得到5条曲线。将这5条曲线画在同一图形 窗口上，并标明每一条曲线。四、设计思想1 .采用矩阵求逆的方法，将系数矩阵求逆，乘以单元矩阵，直接得到未知数。2 .在M文件中使用循环语句，判断是否符合条件，返回值，主程序进行调用3 .将5条曲线分别绘制，plot用不同颜色标志，采用hold on画在一个图中，五、程序代码及注释1 .A=6,3,4;-2,5,7;8,-4,-3;%系数矩阵b=

3、3；-4;-7;x=inv(A)*b%求逆2 .M文件：function n = fun( max )%UNTITLED Summary of this function goes here% Detailed explanation goes herea=1;b=1;while b<maxa=a+1;b=b*a;endn=a-1;end主程序max=input('please input the realmax:');n=fun(max)3 .x=-1:0.01:1;y1=cos(acos(x);plot(x,y1,'r');% 第一条hold ony2

4、=cos(2*acos(x);plot(x,y2,'b');% 第二条hold ony3=cos(3*acos(x);plot(x,y3,'g');% 第三条hold ony4=cos(4*acos(x);plot(x,y4,'y');% 第四条hold ony5=cos(5*acos(x);plot(x,y5,'k');% 第五条六、实验结果1 .结果：b=C3;-4:-7; x-inv (A)*bx =0. 60007, 000040002 .结果：实验二MATLAB基本编程实验一、实验目的及要求1 .回顾数字信号处理的主要内

5、容；2 .掌握利用MATLA皿行信号处理的方法；3 . 了解信号处理工具箱中一些函数的功能；二、实验设备(环境)及要求4 .计算机5 . Matlab软件编程实验平台三、实验内容1 . x(n)=8,5,3,11,7,0,-1,4,2,6,5, -5<n<5 是原序列，设 y(n)是原序列 受到噪声污染并移位了的序列 y(n) = x(n-3)+w(n),其中w(n)是均值为0,方 差为1的高斯随机序列。计算y(n)与x(n)的相关性。2 . 一个线性时不变系统由下面差分方程描述y(n) =0.8y(n -1) x(n)1)求频率响应；2)画出其幅频和相频图；3)如果系统输入为x(

6、n) = cos(0.02nn)u(n),求出在0En W100内的响 应y(n),并画出输入序列和输出序列的曲线图说明。3.设计IIR滤波器(带通，三种方法，fs = 2000Hz通带频率500700Hz, 阶数自选，画频率特性并分析比较)四、设计思想1 .由normrnd函数产生高斯序列，判断函数位进行赋值，产生移位序列，通过函 数xcorr进行互相关处理2 .用freq函数求出频率相应，通过 abs和angle函数求出幅频和相频图，采用 filter函数求出输出序列3 .分别采用butterworth滤波器、椭圆滤波器和cheby滤波器，求出频率特性五、程序代码及注释1.x=8,5,3,

7、11,7,0,-1,4,2,6,5;for n=1:1:11if n<4yy(n)=0;else yy(n)=x(n-3);endendw=normrnd(0,1,1,11);y=yy+w;a=xcorr(x,y);2. fs=1000;b=1；a=1,-0.8;h,f=freqz(b,a,512,fs);mag=abs(h);ph=angle(h);subplot(4,1,1);plot(f,mag);grid;xlabel('frequency(hz)');ylabel('magnitude');subplot(4,1,2);plot(f,ph);gr

8、id;xlabel('frequency(hz)');ylabel('phase');n=1:100;x(n)=cos(0.02*pi*n);y=filter(b,a,x);subplot(4,1,3);stem(x);subplot(4,1,4);stem(y)3.(1)n=10;wn=500 700/1000;b,a=butter(n,wn);h,f=freqz(b,a,256,1000);mag=abs(h);ph=angle(h);subplot(2,1,1);plot(f,mag);grid；xlabel('frequency(hz)'

9、);ylabel('magnitude');subplot(2,1,2);plot(f,ph)；grid;xlabel('frequency(hz)');ylabel('phase');(2) n=10;wn=500 700/1000;b,a=ellip(n,0.5,20,wn)h,f=freqz(b,a,256,1000);mag=abs(h);ph=angle(h);subplot(2,1,1);plot(f,mag);grid;xlabel('frequency(hz)');ylabel('magnitude'

10、;);subplot(2,1,2);plot(f,ph);grid；xlabel('frequency(hz)');ylabel('phase');(3) n=10;wn=500 700/1000;b,a=cheby1(n,0.5,wn);h,f=freqz(b,a,256,1000);mag=abs(h);ph=angle(h);subplot(2,1,1);plot(f,mag);grid；xlabel('frequency(hz)');ylabel('magnitude');subplot(2,1,2);plot(f,ph)

11、；grid;xlabel('frequency(hz)');ylabel('phase');六、实验结果1结果:Figure 1File Edit iew Insert lools Qesktop Window HelpB-l口白。g 环 、非与痘片 I盘I 口目I 口2.结果:Figure 1File Edit View Insert Tools Desktop Window Help3.(1)E| Figure 1 XRie Edit View Insert Tools Desktop Window Help口 m 。q &，c 黝 s * * s

12、国口4 I111111111050100150200250300350400450500frequencyfhz)(2)Figure 1File Edit View Insert Tools Desktop Window Help : U .上/，,门东Ma 二ifreqLiency(hz)i(3)/ Figure 1 File Edit View Insert Tools Desktop Window Help。£3。0|片|0&©3 / |目I 国 国二 Q . y/ r. V K 卜 5 k MKCfrpquncy(hz)实验三 基于MATLAB勺图像处理实验

13、一、实验目的及要求1. 了解图像处理的基本概念和功能；2. 掌握利用MATLA皿行图像处理的方法；3. 了解图像处理工具箱中一些函数的功能；二、实验设备(环境)及要求1 .计算机2 . Matlab软件编程实验平台三、实验内容1 .对barbaran.tif图像进行 DCT变换，分别选取最大的 1/4、1/8、1/16个变换系数(其余置为0),进行反DCT得到重构图像，显示原图像和各重构 图像并分别计算重构图像的峰值信噪比。2 .对cameraman.tif图像至少用3种方法进行边缘增强，给出实验结果并 分析。四、设计思想1 .先用imread函数读取，找出其中最大值，采用dct2函数进行dc

14、t变换，显示 出来，判断小于最大值的变换系数的值赋零，再用 idct反变换处理，改变变换 系数，分别重构图像，最后再计算重构图像和原图像峰值信噪比2 .采用直方图处理、对比度扩展增强、对数变换这三种方式处理，分别采用 histeq、imadjust 和 log 函数。五、程序代码及注释1 .grb=imread('barbaran.tif);a=max(grb(:);i=rgb2gray(grb);subplot(2,1,1);imshow(i);j=dct2(i) subplot(2,1,2);imshow(j);b=a/4;j(abs(j)<b)=0;k=idct2(j);f

15、igure;imshow(k,0 255);A=double(i);B=double(k);m,n=size(i);D=sum(sum(A-B).A2);MSE=D/(m*n);grb=imread('barbaran.tif);a=max(grb(:);i=rgb2gray(grb);subplot(2,1,1);imshow(i);j=dct2(i) subplot(2,1,2);imshow(j);b=a/8;j(abs(j)<b)=0;k=idct2(j);figure;imshow(k,0 255);A=double(i);B=double(k);m,n=size(i)

16、;D=sum(sum(A-B).A2);MSE=D/(m*n);grb=imread('barbaran.tif);a=max(grb(:);i=rgb2gray(grb);subplot(2,1,1);imshow(i);j=dct2(i)subplot(2,1,2);imshow(j);b=a/16;j(abs(j)<b)=0;k=idct2(j);figure;imshow(k,0 255);A=double(i);B=double(k);m,n=size(i);D=sum(sum(A-B).A2);MSE=D/(m*n);2 . i=imread('cameram

17、an.tif);subplot(2,2,1);imshow(i);j,t=histeq(i);subplot(2,2,2);imshow(j);k=imadjust(i,0.15 0.9,0 1);subplot(2,2,3);imshow(k);i=double(i);l=log(i+1);subplot(2,2,4);imshow(l,);六、实验结果1.结果：EJ Figur, T- X'刖菅1日士 rKert Jbols Qek&op 绡ndcw He-lp:J : djk晨一一曲父-复口白=> Q El 曰- Q Xrifk- E番t yiew Insert L

18、oqIs： RpWtQp 由indcnw Help»k 、=由耨0厘日口国0和原图像的峰值噪声比为190和原图像的峰值噪声比为73和原图像的峰值噪声比为202.结果:a： Q Figure 1 XFile Id it "i 电w Insert lools Q«sktop lAJiridow H«lp0 a al 四©，底口因。三种图像，直方图对比度明显，整体较为中和，对比扩展方式导致黑色更黑，黑 色的细节看不到，而对数增强方式，画面偏白，对比也明显。实验四 基于MATLAB申经网络编程实验、实验目的及要求1 , 了解神经网络的基本概念和原理；2

19、 .掌握用MATLA取现神经网络的思路和方法；3 . 了解神经网络工具箱函数的功能。二、实验设备(环境)及要求1 .计算机2 . Matlab软件编程实验平台三、实验内容1、利用2输入的MP模型是否可实现“与”、“或”、“非”和“异或”功能? 若能，编程实现并给出实现各种功能的权值和实验结果，若不能，请说明原 因。2、用人工神经网络拟合函数f (x)= sin(x) 0.46e-°.15x cos(1.2X), 0 x 4二说明：1)网络结构为三层(输入层、1个隐层和输出层)2 )获取两组数据，一组作为训练集，一组作为测试集3 )用训练集训练网络4 )用测试集检验训练结果四、设计思想

20、1 .使用MP模型解决此问题，选择初值，计算误差，更新全值，对所有模式 进行所有训练，直到输出满足。2.使用三层BP网络来完成函数逼近。因为函数为一元函数，所以输入层有 一个输入，输出层有一个输出，隐层神经元的个数为10。五、程序代码及注释1. p=0 0 1 1；0 1 0 1； % 与t=0 0 0 1;d=0 1 0 1;w1=0.2;w2=0.5;yita=-0.1;theta=0.1;while isequal(t,d)for j=1:1:4w1=w1+yita*(d(j)-t(j)*p(1,j);w2=w2+yita*(d(j)-t(j)* p(2,j); theta=theta+

21、yita*(d(j)-t(j); d(j)=w1*p(1,j)+w2*p(2,j)+theta; d(j)=round(d(j);endendp=0 0 1 1;0 1 0 1;% 或t=0 1 1 1;d=0 1 0 1;w1=0.2;w2=0.5;yita=-0.1;theta=0.1;while isequal(t,d)for j=1:1:4w1=w1+yita*(d(j)-t(j)*p(1,j);w2=w2+yita*(d(j)-t(j)* p(2,j); theta=theta+yita*(d(j)-t(j);d(j)=w1*p(1,j)+w2*p(2,j)+theta; d(j)=

22、round(d(j);endendp=0 0 1 1;0 1 0 1;% 异或t=0 1 1 0;d=0 1 0 1;w1=0.2;w2=0.5;yita=-0.1;theta=0.1;while isequal(t,d)for j=1:1:4w1=w1+yita*(d(j)-t(j)*p(1,j);w2=w2+yita*(d(j)-t(j)* p(2,j); theta=theta+yita*(d(j)-t(j);d(j)=w1*p(1,j)+w2*p(2,j)+theta; d(j)=round(d(j);end end2. x=0:0.01:4*pi;%画出模拟曲线y=sin(x)+0.

23、46*exp(-0.15*x).*cos(1.2*x);figure(1);plot(x,y,'g');hold on;N=50;% 初始化预测集样本数P1=0:0.2:4*pi; %训练集样本点P2=(4*pi)*rand(1,N);%预测集样本点%计算训练集和预测集对应的目标向量 T1,T2 T1= sin(P1)+0.46*exp(-0.15*P1).*cos(1.2*P1); T2= sin(P2)+0.46*exp(-0.15*P2).*cos(1.2*P2);%建立网络net = newff(P1,T1,1 6);%设置训练参数net.trainParam.show

24、 = 50;net.trainParam.lr = 0.05;net.trainParam.mc = 0.95;net.trainParam.epochs = 400;net.trainParam.goal = 1e-8;net,tr=train(net,P1,T1); % 训练网络 A=sim(net,P2); %对预测集进行预测plot(P1,T1,'r+',P2 Ab');六、实验结果1 .与：w1=0.2 w2=0.4 theta=0或：w1=0.3 w2=0.5 theta=0.2无法实现非功能，由于非只需要一个输入异或：w1=0.1 w2=0.1 theta

25、=0.22 .Figure 1 XAle Edit View Insert Tools Desktop i.Vindow Helpn目”彘| Q|W 6婆£|国|口国| 口.0.8060.40.20- 0.2- 0.4- 0.6- 0.8- 1024681012 Uir图中的蓝色曲线是所需模拟函数的曲线，红色+'为训练集的样本点，而蓝色的.是预测集P2经过网络预测的结果A,即（P2, A）。我们可以 发现模拟的结果很好。实验五 MATLAB的综合实验,、实验目的及要求培养学生利用Matlab解决专业问题的能力。、实验设备（环境）及要求1 .计算机2 . Matlab软件编程实

26、验平台三、实验内容（三题中选择一题）1、实现一个数字信号处理的仿真系统，通过该系统可以方便的验证信号处理 所学的基本内容，要求程序具有界面并实现以下功能：1）能产生或得到各种数字信号（sin、方波、三角波、语音、噪声及其叠 加）；2）具有根据需求设计低通、高通、带通和带阻滤波器的功能；3）具有对数字信号进行DFT、DCT和DWT变换和经典功率谱估计功能；4）产生或输入数字信号，显示时域、变换域及功率谱估计波形，在这个 信号上叠加噪声，通过滤波器对其降噪，得到输出信号的频域特性和 时间序列。2、基于数字图像处理，实现一个汽车标志定位和分割的仿真系统。要求系统 具有界面并实现以下功能：1）读入包含

27、汽车标志的汽车图像；2）预处理及汽车标志定位；3）多种图像分割功能；4）形态学滤波等功能；3、结合自己的研究方向，实现一个神经网络应用的实例，要求用至少3种方 法实现（可以包括不同神经网络方法或经典方法），并对实验结果进行比 较分析。四、设计思想1 .实现一个数字信号处理的仿真系统根据数字信号处理的仿真系统要求，设计界面框图，安排界面布局图像二值化用GUI按照设计进行界面交互组件添加并设置组件属性对回调函数进行编程，实现题设功能调整界面并调试程序五、程序代码(界面除外)及注释function varargout = renliang(varargin)% Begin initializatio

28、n code - DO NOT EDIT gui_Singleton = 1;gui State = struct('gui Name', mfilename,'gui_Singleton', gui_Singleton,'gui_OpeningFcn', renliang_OpeningFcn,'gui_OutputFcn', renliang_OutputFcn,'gui_LayoutFcn', 口，'gui_Callback', );if nargin && ischar(va

29、rargin1)gui_State.gui_Callback = str2func(varargin1);endif nargoutvarargout1:nargout = gui_mainfcn(gui_State, varargin:);elsegui_mainfcn(gui_State, varargin:);end% End initialization code - DO NOT EDIT% - Executes just before renliang is made visible.function renliang _OpeningFcn(hObject, eventdata,

30、 handles, varargin)% Choose default command line output for renlianghandles.output = hObject;% Update handles structure guidata(hObject,handles);% UIWAIT makes renliang wait for user response (see UIRESUME)% - Outputs from this function are returned to the command line.function varargout = renliang

31、_OutputFcn(hObject, eventdata, handles)% Get default command line output from handles structurevarargout1 = handles.output;% - Executes on button press in checkboxl.function checkbox1_Callback(hObject, eventdata, handles)%£弦波输入%- Executes during object creation, after setting all properties. fu

32、nction checkbox1_CreateFcn(hObject, eventdata, handles)function edit1_Callback(hObject, eventdata, handles)%- Executes during object creation, after setting all properties.function edit1_CreateFcn(hObject, eventdata, handles) if ispc && isequal(get(hObject,'BackgroundColor'), get(0,&

33、#39;defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white'); endfunction edit6_Callback(hObject, eventdata, handles)%正弦波频率%- Executes during object creation, after setting all properties.function edit6_CreateFcn(hObject, eventdata, handles) if ispc && iseq

34、ual(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white'); end% - Executes on button press in checkbox1.function checkbox2_Callback(hObject, eventdata, handles)%T波输入%- Executes during object creation, after sett

35、ing all properties.function checkbox2_CreateFcn(hObject, eventdata, handles)function edit2_Callback(hObject, eventdata, handles)%T波幅值%- Executes during object creation, after setting all properties.function edit2_CreateFcn(hObject, eventdata, handles) if ispc && isequal(get(hObject,'Back

36、groundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white'); endfunction edit7_Callback(hObject, eventdata, handles)%T波频率%- Executes during object creation, after setting all properties.function edit7_CreateFcn(hObject, eventdata, handles

37、) if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white');end% - Executes on button press in checkboxl.function checkbox3_Callback(hObject, eventdata, handles)%三角波输入%- Executes during ob

38、ject creation, after setting all properties. function checkbox3_CreateFcn(hObject, eventdata, handles)function edit3_Callback(hObject, eventdata, handles)%三角波幅值%- Executes during object creation, after setting all properties.function edit3_CreateFcn(hObject, eventdata, handles) if ispc && is

39、equal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white'); endfunction edit8_Callback(hObject, eventdata, handles)%三角波频率%- Executes during object creation, after setting all properties.function edit8_CreateFcn

40、(hObject, eventdata, handles) if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white'); end% - Executes on button press in checkbox1.function checkbox4_Callback(hObject, eventdata, handle

41、s)%语音信号输入一%- Executes during object creation, after setting all properties. function checkbox4_CreateFcn(hObject, eventdata, handles)function edit4_Callback(hObject, eventdata, handles)%语音信号幅帝%- Executes during object creation, after setting all properties.function edit4_CreateFcn(hObject, eventdata

42、, handles) if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white');end% - Executes on button press in checkboxl.function checkbox5_Callback(hObject, eventdata, handles)%fi噪声输入%- Executes

43、 during object creation, after setting all properties.function checkbox5_CreateFcn(hObject, eventdata, handles)function edit5_Callback(hObject, eventdata, handles)加噪声幅值%- Executes during object creation, after setting all properties.function edit5_CreateFcn(hObject, eventdata, handles) if ispc &

44、& isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white');end% - Executes on button press in pushbutton1.function pushbutton1_Callback(hObject, eventdata, handles)%W号输入控制一global N;%信号取样数N=110033;global

45、 n;%信号取样点n=1:N;sgn1=get(handles.checkbox1,'value');%5类信号选择与否sgn2=get(handles.checkbox2,'value');sgn3=get(handles.checkbox3,'value');sgn4=get(handles.checkbox4,'value');sgn5=get(handles.checkbox5,'value');rag1=str2num(get(handles.edit1,'string');%5类信号幅值

46、输入rag2=str2num(get(handles.edit2,'string');rag3=str2num(get(handles.edit3,'string');rag4=str2num(get(handles.edit4,'string');rag5=str2num(get(handles.edit5,'string');frq1=str2num(get(handles.edit6,'string');%5类信号频率输入frq2=str2num(get(handles.edit7,'string&#

47、39;);frq3=str2num(get(handles.edit8,'string');x1=sin(frq1*pi*n/N*2);%产生正弦波x2=square(frq2*pi*n/N*2);% 产生方波x3=sawtooth(frq3*pi*n/N*2,0.5);%产生三角波global x4;%读取语音信号global fs;x4,fs=wavread('speech_dft.wav');x4=x4'x5=2*rand(1,N)-1;%产生白噪声global x;%选择信号叠加的输入信号x=rag1*sgn1.*x1+rag2*sgn2.*x2

48、+rag3*sgn3.*x3+rag4*sgn4.*x4+rag5*sgn5.* x5;axes(handles.axes1);plot(x)title('输入信号时间序列)；% - Executes on button press in radiobutton1.function radiobutton1_Callback(hObject, eventdata, handles)%54J? DFT变换% - Executes on button press in radiobutton2.function radiobutton2_Callback(hObject, eventdat

49、a, handles)%54JD DC侬换% - Executes on button press in radiobutton3.function radiobutton3_Callback(hObject, eventdata, handles)%选择DW夜换% - Executes on button press in pushbutton2.function pushbutton2_Callback(hObject, eventdata, handles)%寸输入信号进行 DFT DCE口 DW1变换global N;%全局变量global n;global x;slect1=get(

50、handles.radiobutton1,'value');%3种变换选择slect2=get(handles.radiobutton2,'value');slect3=get(handles.radiobutton3,'value');if slect1%选择DFT变换y=fft(x,N);%DFT 变换 axes(handles.axes2);plot(abs(y(1:(N+1)/2)title(' 输入信号的DFT变换')；else if slect2%选择 DC侬换y=dct(x);%DCT 变换axes(handles.

51、axes2);plot(abs(y)title('输入信号的DC侬换')；else if slect3%选择 DWT£换cA,cD=dwt(x,'db1');%DWT变换%近似系数CA1和细节系数CD1axes(handles.axes2);plot(1:(N+1)/2,abs(cA),1:(N+1)/2,abs(cD)legend('cA','cD');title('输入信号的DWK换')；end end end% - Executes on button press in radiobutton4.f

52、unction radiobutton4_Callback(hObject, eventdata, handles)%选择低通滤波set(handles.edit9,'Enable','off);%截止低频输入框灰暗显示set(handles.edit10,'Enable','on');%截止高频输入框使能% - Executes on button press in radiobutton5.function radiobutton5_Callback(hObject, eventdata, handles)%选择低通滤波一set(ha

53、ndles.edit9,'Enable','on');%截止低频输入框使能set(handles.edit10,'Enable','off);%截止高频输入框灰暗显示% - Executes on button press in radiobutton6.function radiobutton6_Callback(hObject, eventdata, handles)%选择低通滤波一set(handles.edit9,'Enable','on');%截止低频输入框使能set(handles.edit10

54、,'Enable','on');%截止高频输入框使能function edit9_Callback(hObject, eventdata, handles)%截止低频输入%- Executes during object creation, after setting all properties. function edit9_CreateFcn(hObject, eventdata, handles)if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'de

55、faultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white');endfunction edit10 Callback(hObject, eventdata, handles)止高频输入%- Executes during object creation, after setting all properties.function edit10_CreateFcn(hObject, eventdata, handles)if ispc && isequal(get

56、(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')set(hObject,'BackgroundColor','white'); end% - Executes on button press in pushbutton3.function pushbutton3_Callback(hObject, eventdata, handles)%实现低通、高通、通通滤波，得到输出信号的频域特性和时间序列global N;% 全局变量global x;P=5;%滤波结束slect4=get(handles.radiobutton4,'value');%滤波类型选择slect5=get(handles.radiobutton5,'value');slect6=get(handles.radiobutton6,'value');if slect4%选择低通滤波fs=str2num(get(handles.edit10,'string');%得到截止高频b,a=butter(P,fs/N