How to design aFIR filter without filter function

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farhad vaseghi
farhad vaseghi 2020-3-13
评论： farhad vaseghi 2020-3-13
please help me implement this as function to take a,b,x and give me y
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farhad vaseghi
farhad vaseghi 2020-3-13
I wanna impeliment this whith a seprate function
and without,without any use of filter() function!!!!!!!!!!!

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Sriram Tadavarty
Sriram Tadavarty 2020-3-13
编辑：Sriram Tadavarty 2020-3-13
Hi Farhad,
This code should do what is asked for. Since, you asked for FIR filter, a will be a scalar with value 1.
function y = filterbax(b,a,x)
% The function expects inputs to be column vectors
M = length(b);
N = length(a);
xbuffer = [];
ybuffer = [];
for i = 1:length(x)
xbuffer = [x(i);xbuffer];
if length(xbuffer) < M
index = length(xbuffer);
else
index = M;
end
if length(ybuffer) < N-1
yindex = length(ybuffer);
else
yindex = N-1;
end
y(i) = (1/a(1)).*(sum(b(1:index).*xbuffer(1:index)) - sum(a(2:yindex+1).*ybuffer(1:yindex)));
ybuffer = [y(i);ybuffer];
end
y = y(:); % Return as column vector
end
Note that more optimizations can be done, but this should work.
% In command prompt,
% try the following
>> b = [2,3];
>> a = [1,0.2];
>> x = randn(10000,1);
>> y = filterbax(b,a,x); % Custom function
% Compare the output from custom written function and MATLAB function
>> y1 = filter(b,a,x); % MATLAB function
>> max(abs(y-y1).^2)
Hope this helps.
Regards,
Sriram
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Sriram Tadavarty
Sriram Tadavarty 2020-3-13
Hi farhad, This is not the same filter function. The name of the function is placed as filterbax which is independent of filter. The bottom code in the answer is just the test with the inbuilt Matlab function. Hope it clears. Regards, Sriram
farhad vaseghi
farhad vaseghi 2020-3-13
Tanks Sriram
your a great man
thats the answer
you helped me this day i wish god bless you
tanks bro

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