Ideal FIR Low Pass Filter without using inbuilt MATLAB function

%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