how can i put the type de fir1 window as input in fuction?

I have a function which calculates the filter coefficients,return the frequency response .... But i want to see the difference between each type of window. my function is called like this:

[c1 c9 MGhann] =CalculateFilterCoeff(N,D,hann(N),hann(N-1))

 and the function is :
%----------------------------------------------------------------------------------------------
%----------------------------------------------------------------------------------------------

function [c1 c9 MargeGain] = CalculateFilterCoeff(Nelec,DinterElec,windtype1,windtype2)
w1= windtype1
w2= windtype2

%%calcul des coefficients des fitres utilisant fir1  
c1 =fir1(Nelec-1,2*95*DinterElec,'low',w1); 
c9 =fir1(Nelec-2,2*95*DinterElec,'high',w2);

%%Dessin des réponse fréquentielle des filtres appliqués 
[h1 w1]=freqz(c1*sqrt(2),1,512);
[h9 w2]=freqz(c9*sqrt(2),1,512);

%%calcul du marge de gain entre Filtre passe-bas et passe-haut 
MargeGain = []
y=find(f9>=50, 1, 'first')
MargeGain(1)=20*log10(abs(h9(y)))

end

%------------------------------------------------------------------------------------------------------------------------------------------------------------------------ %------------------------------------------------------------------------------------------------------------------------------------------------------------------------

THE PROBLEM is that i want to prevent to prevent to specify the window length (N) because in my function i want it with different length depending on the value of N. So if N is even: [c1 c9 gain] =CalculateFilterCoeff(N,D,window(N),window(N-1)) else % N is odd [c1 c9 gain] =CalculateFilterCoeff(N,D,window(N),window(N))

I can't but the type of window alone such as [c1 c9 gain] =CalculateFilterCoeff(N,D,hann) and inside the function deside which is the length because it returns that error message: ??? Error using ==> hann at 15 Not enough input arguments.

Thanks for helping to solve this problem

[Wayne King]

Can you please show how you are calling CalculateFilterCoeff() at the command line?

Show us what kind of input values you want to give it. I don't understand your post as it currently stands.

[Maria]

for this moment i'm calling it like this :

[c1 c9 MGhann] = CalculateFilterCoeff(N,D,hann(N),hann(N-1))

suppose that i defined N=20, D=3e-3 what i need to use the window type as input arfument without the N value, i want it inside the function. so

function [c1 c9 MargeGain] =CalculateFilterCoeff(Nelec,DinterElec,windtype1)

if mod(N,2) == 0
w1= windtype1(N)
w2= windtype1(N-1)
else 
w1= windtype1(N)
w2= windtype1(N)
end

c1 =fir1(N-1,2*95*D,'low',w1); % Fcn=Fc*2/Fsech = Fc*2*d
c9 =fir1(N-2,2*95*D,'high',w2);
end

[Wayne King]

so where is the windtype1 function? We need to see that.

[Maria]

its in that line where is written :

w1=windtype1(N)

then i use it for the fir1

c1 =fir1(N-1,2*95*D,'low',w1)

[Maria]

lets make it more simple, if i have that function:

function [coef]= CalFilterCoef(N,D,windtype1)
 w1=windtype1(N)
 c1 =fir1(N-1,2*95*D,'low',w1);
[h1 w1]=freqz(c1*sqrt(2),1,512);

end

when i want to call it by writing in the command window :

CalFilterCoef(20,3e-3,hann)

I have that error ! ??? Error using ==> hann at 15 Not enough input arguments.

I dont want to put the length of window in the function thanks

Answer 1

[Wayne King]

function [c1 c9] =CalculateFilterCoeff(N,D,windtype1)

if (mod(N,2) == 0)
w1= feval(windtype1,N);
w2= feval(windtype1,N-1);
else 
w1= feval(windtype1,N);
w2= feval(windtype1,N);
end

c1 =fir1(N-1,2*95*D,'low',w1); % Fcn=Fc*2/Fsech = Fc*2*d
c9 =fir1(N-2,2*95*D,'high',w2);
end

Then call the function like this:

N = 20;
D = 0.003;
[c1 c9 ] = CalculateFilterCoeff(N,D,@hann);
[c1 c9 ] = CalculateFilterCoeff(N,D,@hamming);

Note I removed the MargeGain part because you had some problems there.

[Maria]

Thank you very much i like this solution ! But i solved it too by declaring the input argument windtype as char ('hann') then i created another m file which uses a switch case of all window type. But urs is easier :) Thank you