plotting the magnitude and phase response of a 3rd order low pass filter defined by the equation y(n)

Using MATLAB implement a code to plot the magnitude and phase response of a 3rd order low pass filter defined by the equation:

y(n) = 0.0181x(n)+0.0543x(n-1)+0.0543x(n-2)+0.0181x(n-3)+1.76y(n-1)-1.1829y(n-2)+0.2781y(n-3)

Answer 1

[Chunru]

% y(n) = 0.0181x(n)+0.0543x(n-1)+0.0543x(n-2)+0.0181x(n-3)+1.76y(n-1)-1.1829y(n-2)+0.2781y(n-3)
b = [0.0181  0.0543   0.0543    0.0181];
a = [1  -1.76   1.1829      -0.2781];
freqz(b, a, 1024);

[Emmanuel Busina]

Thanks Chunru. Could you please enlighten me why you included 1024 in freqz section.

[Chunru]

n=1024 for number of frequency points in evaluating frequenct response. doc freqz for details.

[Kritika Gupta]

what is 1024 in freqz(nz,dz,1024*1024,600e3)