画伯德图可以用simulink或者matlab自带的bode函数：
P=bodeoptions;P.Grid='on';P.XLim={[1e-2,100]};%设置横轴范围P.FreqUnits='Hz';%将横坐标单位换位HZP.YLim={[-30,3],[-135,10]};%设置纵轴范围num1=[30,369.8,1367];den1=[2.152E-4,0.2704,29.99,358.9,1367];Gx_validation=tf(num1,den1);[mag,phase,wout]=bode(Gx_validation,P)%bode(Gx_validation,P)margin(Gx_validation)但是其不能准确输出和在图中标出谐振点和-3dB的点（只能用figure下的游标数据来标），下面根据伯德图的定义，直接用传递函数G(iw)，算出其幅值和幅角：
%this function is to calculate the bode diagram without using bode function%directly.figure(1);%% -----限定坐标轴输出范围-----axisxmin=1e-2;axisxmax=1e2;axisyminmag=-inf;axisymaxmag=4;axisyminpha=-inf;axisymaxpha=45;%% -----幅频图------subplot(2,1,1);f=logspace(-2,2,10000); %频率采样，利用logspace在横坐标log之后均匀取点，防止线性取点后画图时的不均匀w=f*2*pi;wi=complex(0,w); %使角频率和虚数单位结合%输入系统传递函数G=(30*(wi).^2+127.9*wi+163.6)./(1.244e-3*(wi).^4+0.7818*(wi).^3+29.99*(wi).^2+124.1*wi+163.6) ;magnitude=20*log10(abs(G)); %幅度换算为dB单位semilogx(f,magnitude);title('G_{a_Z} Bode Diagram');axis([axisxmin,axisxmax,axisyminmag,axisymaxmag]);box on;%xlabel('frequency (Hz)','Fontweight','bold','FontSize',20);ylabel('Magnitude (dB)','Fontweight','bold','FontSize',20);grid minor; %加密网格set(gca,'xticklabel',[]) %去掉横坐标数字set(gca,'GridLineStyle','-','XGrid','on','YGrid','on'); %添加横坐标和纵坐标的网格set(gca,'FontSize',10,'Fontweight','bold'); %调节坐标轴字体大小粗细hold on;%% -----相频图------subplot(2,1,2);phase=angle(G)*180/pi; %取虚数幅角值，并转换弧度为角度semilogx(f,phase);axis([axisxmin,axisxmax,axisyminpha,axisymaxpha]);box on;xlabel('frequency (Hz)','Fontweight','bold','FontSize',10);ylabel('Phase (deg)','Fontweight','bold','FontSize',10);grid minor; %加密网格set(gca,'GridLineStyle','-','XGrid','on','YGrid','on'); %添加横坐标和纵坐标的网格set(gca,'FontSize',10,'Fontweight','bold'); %调节坐标轴字体大小粗细hold on; %% -----添加谐振点-----subplot(2,1,1);[magmax,fmax] = max(magnitude); %谐振点为幅频曲线的极值点fmax = f(fmax);plot(fmax,magmax,'o','LineWidth',2,'MarkerSize',5,'MarkerEdgeColor','k')text(fmax,magmax-2,sprintf('Resonance point:n(%.3f Hz, %.3f dB)',fmax,magmax),... 'VerticalAlignment','top','HorizontalAlignment','right')%'VerticalAlignment','bottom'hold on;%% -----添加-3dB带宽-----B=abs(magnitude+3);[x,index]=sort(B); %为了得到最接近-3dB的值，先对绝对值进行排序，index为排序前的坐标值mag_3db=magnitude(index(1));f_3db=f(index(1));plot(f_3db,mag_3db,'o','LineWidth',2,'MarkerSize',5,'MarkerEdgeColor','r')text(f_3db,mag_3db,sprintf('Cut-off point:n(%.3f Hz, %.3f dB)',f_3db,mag_3db),... 'VerticalAlignment','bottom','HorizontalAlignment','left') %在目标坐标点处添加文字