NF4.m

function y = doFilter(x)
%DOFILTER Filters input x and returns output y.

% MATLAB Code
% Generated by MATLAB(R) 9.7 and DSP System Toolbox 9.9.
% Generated on: 02-Apr-2020 12:17:08

%#codegen

% To generate C/C++ code from this function use the codegen command.
% Type 'help codegen' for more information.

persistent Hd;

if isempty(Hd)
    
    % The following code was used to design the filter coefficients:
    %
    % Fpass1 = 48;   % First Passband Frequency
    % Fstop1 = 49;   % First Stopband Frequency
    % Fstop2 = 50;   % Second Stopband Frequency
    % Fpass2 = 52;   % Second Passband Frequency
    % Apass1 = 1;    % First Passband Ripple (dB)
    % Astop  = 60;   % Stopband Attenuation (dB)
    % Apass2 = 1;    % Second Passband Ripple (dB)
    % Fs     = 200;  % Sampling Frequency
    %
    % h = fdesign.bandstop('fp1,fst1,fst2,fp2,ap1,ast,ap2', Fpass1, Fstop1, ...
    %                      Fstop2, Fpass2, Apass1, Astop, Apass2, Fs);
    %
    % Hd = design(h, 'ellip', ...
    %     'MatchExactly', 'stopband', ...
    %     'SystemObject', true);
    
    Hd = dsp.BiquadFilter( ...
        'Structure', 'Direct form II', ...
        'SOSMatrix', [1 0.060139596889612 1 1 0.115515035893294 ...
        0.985601347034277; 1 -0.060139596889613 1 1 -0.115515035893295 ...
        0.985601347034277; 1 0.0386577726950758 1 1 0.128040582471055 ...
        0.926730436294425; 1 -0.038657772695077 1 1 -0.128040582471056 ...
        0.926730436294425; 1 -1.22706813782029e-16 1 1 -1.10314996143204e-16 ...
        0.798025598466977], ...
        'ScaleValues', [0.742075406338059; 0.742075406338059; ...
        0.961415246879674; 0.961415246879674; 1.60514559123974; 1]);
end

s = double(x);
y = step(Hd,s);