MATLAB Examples

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## Sample parameters

clear all; clc; freq1 = 50; % Frequency in Hertz freq2 = 100; T1 = 1/freq1; % periods T2 = 1/freq2; Nt = 50; % Numberof samples in time per period dt = min(T1,T2)/Nt; % time step t=0:dt:(10*max(T1,T2)); Nrepetition=1; NFFT=Nrepetition*length(t); Fs = NFFT; % Sampling frequency T = 1/(Fs); % Sample time isVideoOn = 0; % To turn on/off for jpeg dumpong which is later for generating the video iBufferTime=100; % Buffer time steps to stop during progression (for animation purposes) func=zeros(1,length(t)); func2=zeros(1,length(t)); for Iteration=1:5 for it=1:(length(t)+iBufferTime) 
 if (it <=length(t)) func(it)=sin(2*pi*freq1*t(it)); if (Iteration == 2) func2(it)= 1.5*sin(2*pi*freq2*t(it)); end if (Iteration == 3) func2(it)= 1.5*sin(2*pi*2*freq2*t(it)); end if (Iteration == 4) L2=floor(length(t)/2); if (it <=L2) func2(it)= 1; else func2(it)= 0; end end if (Iteration == 5) L2=floor(length(t)/2); if (it <L2 || it >= L2) func2(it)= 0; end end else % Keep Same (do nothing) - freezing in time end 
 Lw=2; Fs=10; f6=figure (6); clf; set(gcf,'Color',[1 1 1]); sp1=subplot(10,1,1:3); set(gca,'FontSize',Fs); plot(t,func,'b','LineWidth',Lw,'LineSmoothing','on'); grid on; hold on; text(-0.018,0.5,1,'f_1(t) \rightarrow','FontSize',Fs+2,'Color','b') plot(t,func2,'r','LineWidth',Lw,'LineSmoothing','on'); grid on; ylim([-2 2]) set(gca,'xticklabel',[]); set(gca,'OuterPosition',[ -0.04 0.75 1.13 0.25]) text(-0.018,-0.5,1,'f_2(t) \rightarrow','FontSize',Fs+2,'Color','r') set(sp1,'Color',[0.9608 0.9765 0.9922]); funcSum=func+func2; sp3=subplot(10,1,4:6); set(gca,'FontSize',Fs); plot(t,funcSum,'k','LineWidth',Lw,'LineSmoothing','on'); grid on; xlabel('time (sec)'); ylim([-2.5 2.5]) set(gca,'OuterPosition',[ -0.04 0.45 1.13 0.3]) text(-0.024,0,1,'f_1(t)+f_2(t) \rightarrow','FontSize',Fs+2) set(sp3,'Color',[0.8941 0.9412 0.9020]); funcSum_rep=[]; func_rep=[]; for ik=1:Nrepetition funcSum_rep=[funcSum_rep funcSum]; func_rep=[func_rep func]; end FD_funcSum = fft(funcSum_rep,NFFT)/NFFT; FD_func = fft(func_rep,NFFT)/NFFT; f=(0:(NFFT-1))/(NFFT*dt); 

## Take FFT and plot single-sided amplitude spectrum.

 sp4=subplot(10,1,7:10); set(gca,'FontSize',Fs); stem(f(1:(floor(NFFT/2)+1)),2*abs(FD_func(1:(floor(NFFT/2)+1))),'--bx','LineWidth',Lw); hold on; grid on; stem(f(1:(floor(NFFT/2)+1)),2*abs(FD_funcSum(1:(floor(NFFT/2)+1))),'-ko','LineWidth',Lw); plot(f(1:(floor(NFFT/2)+1)),2*abs(FD_func(1:(floor(NFFT/2)+1))),':b','LineWidth',Lw-1,'LineSmoothing','on'); hold on; grid on; plot(f(1:(floor(NFFT/2)+1)),2*abs(FD_funcSum(1:(floor(NFFT/2)+1))),':k','LineWidth',Lw-1,'LineSmoothing','on'); xlabel('Frequency (Hz)') xlim([-1 256]) set(gca,'OuterPosition',[ -0.04 0.01 1.13 0.42]) Ylim4=get(sp4,'Ylim'); t1=text(-31,1.25,10,'{\bf |FFT\{f_1(t)+f_2(t)\}| }','FontSize',Fs+2); set(t1,'BackgroundColor',[0.8 0.866667 0.776471]); legend('|FFT\{f_1(t)\}|','|FFT\{f_1(t)+f_2(t)\}|'); set(sp4,'Color',[0.905882 0.905882 0.905882]); ylim([0 1.5]) 

## Dumping snapshots to jpg files

 set(gcf, 'InvertHardCopy', 'off'); if (isVideoOn == 1) set(gcf,'PaperPositionMode','auto'); % set(gcf,'PaperUnits','inches','PaperPosition',[0 0 48 27]) Name='JPEG/FFTAnimationStem_'; itx=it + (Iteration-1)*(length(t)+iBufferTime); disp(['itx= ' num2str(itx)]); if (itx <10) print (f6, '-djpeg100', [Name '000' num2str(itx) '.jpg'],'-r96') elseif (itx>=10 && itx <100) print (f6, '-djpeg100', [Name '00' num2str(itx) '.jpg'],'-r96') elseif (itx>=100 && itx <1000) print (f6, '-djpeg100', [Name '0' num2str(itx) '.jpg'],'-r96') else print (f6, '-djpeg100', [Name '' num2str(itx) '.jpg'],'-r96') end end pause(0.01); 
 end end