Real-Time Digital Signal Processing from MATLAB® to C with the TMS320C6x DSPs, Second Edition, 2nd Edition

194 CHAPTER 10. PROJECT 1: GUITAR SPECIAL EFFECTS

Listing 10.3: A MATLAB IIR comb filter example.

1 % Method using the filter command

3 R=round ( R ); % ensure R is an integer before proceeding

A=zeros(1 ,R+1) ; % correct length of vector A

5 A (1)=1; A ( R+1)=−alpha ;

% A vector is now ready to use filter command

7 B=zeros (1 ,R+1) ; % correct length of vector B

B ( R+1)=1; % use "B =1;" for other IIR version

9 % B vector is now ready to use filter command

y=filter( B , A , x );

Lines 4 and 5 ensure the A coefficient vector has the proper length and values (take note

of the sign needed for alpha). Lines 7 and 8 set up the B vector properly. If you would