%equiripple FIR filter
Fs=1000;
Fp=input('Input the pass band frequency Fp= ');
Fst=input('Input the stop band frequency Fst= ');
Ap=input('Input the pass band attenuation Ap= ');
Ast=input('Input the stop band attenuation Ast= ');
d=fdesign.lowpass('Fp,Fst,Ap,Ast');
Hd=design(d,'equiripple');
fvtool(Hd);

%ideal low pass linear phase FIR filter%
wc=input('Input the cut-off frequency in radians(less than pi)');
M=input('Input the length of ideal filter');
if wc>pi
    error('cut-off frequency should be less than pi')
    return
end
alpha=(M-1)/2;
n=0:1:(M-1);
m=n-alpha+eps;
hd=sin(wc*m)./(pi*m);
if nargout==0
    stem(n,hd);
    title('Impulse response of ideal low pass filter');
    xlabel('n');
    ylabel('hd(n)');
end