I have to change the below code to do the following: a.) passes all frequencies above 500HZ,b.)passes all frequencies below 3000HZ, c.) rejects all frequencies between 1500 to 2500 HZ. I can't get the originally code to function. Can you help me through this? Thank you.

% filternoise.m filter a noisy signal three ways time=3; % length of time Ts=1/10000; % time interval between samples x=randn(1,time/Ts); % generate noise signal figure(1) ,plotspec(x,Ts); % draw spectrum of input freqs=[0 0.2 0.21 1]; amps=[1 1 0 0]; b=firpm(100,freqs,amps); % specify the LP filter ylp=filter(b,1,x); % do the filtering figure(2),plotspec(ylp,Ts) % plot the output spectrum freqs=[0 0.24 0.26 0.5 0.51 1]; amps=[0 0 1 1 0 0]; b=firpm(100,freqs,amps); % BP filter ybp=filter(b,1,x); % do the filtering figure(3),plotspec(ybp,Ts) % plot the output spectrum freqs=[0 0.74 0.76 1]; amps=[0 0 1 1]; b=firpm(100,freqs,amps); % specify the HP filter yhp=filter(b,1,x); % do the filtering figure(4),plotspec(yhp,Ts) % plot the output spectrum% %Here's how the figure filternoise.eps was actually drawn N=length(x); % length of the signal x t=Ts*(1:N); % define a time vector ssf=(-N/2:N/2-1)/(Ts*N); % frequency vector fx=fftshift(fft(x(1:N))); figure(5), subplot(4,1,1), plot(ssf,abs(fx)) xlabel('magnitude spectrum at input') fyl=fftshift(fft(ylp(1:N))); subplot(4,1,2), plot(ssf,abs(fyl)) xlabel('magnitude spectrum at output of low pass filter') fybp=fftshift(fft(ybp(1:N))); subplot(4,1,3), plot(ssf,abs(fybp)) xlabel('magnitude spectrum at output of band pass filter') fyhp=fftshift(fft(yhp(1:N))); subplot(4,1,4), plot(ssf,abs(fyhp)) xlabel('magnitude spectrum at output of high pass filter')