Matlab code for FIR filter design

plot fir filter with matlab

my project is about FIR filter design by the FFT algorithm,

I have some problem in writing code in Matlab.
if any body could help me I'll really be tankful.

please copy paste this code in your Matlab software(ver.7) & run it.

f = [0 0.4 0.6 1]; m = [1 1 0 0];
h,1) = fir2(31,f,m) ; %time domain FIR filter
plot(b);
hold on
plot(I,h,1),'r');grid;
title('h0[n]','fontweight','bold');
xlabel('time');ylabel('amplitude');

[Hid,w] = freqz(b,1,64) ; %frequency domain
figure
plot(f,m,w/pi,abs(Hid));
legend('Ideal','fir2 Designed')
title('Comparison of Frequency Response Magnitudes,Hid(w)');
xlabel('frequency');ylabel('amplitude');grid;;

H,1)=abs(fft(h,1),512));
figure
w=-256:255;
u=w';
plot(u,H,1));title('FFT')

Ed)=.05;
for k=1:4
H,k) =abs(fft(h,k),512));
if H,k)> (H,1)+Ed)) G,k)=H,1) + Ed) ;
elseif H,k)< (H,1)-Ed)) G,k)=H,1) - Ed) ;
elseif (H,1)-Ed)) <= H,k)<= (H,1)+Ed)) G,k)=H,k);
end
g,k)=ifft( G,k),32);
i=-N:N;
h,(k+1))=g,k) ;
%figure
%plot(i,h,(k+1)))
delta=(h,k+1)-h,k));
%if delta>Ed,1), break, end
end

the problem : Matlab computes G,k) & that is equal to zero

BUT WHY?????????????????

I'll never forgot your help. thank you

my mail: barg_ieee2@yahoo.com