MATLAB code for spectrum sensing for cognitive radio

if true
  % code
endthis is my matlab code but it did not work for me even if i download it from internet. when i try to run in matlab it says character values loop is resizing continuously so it tell me to fix it but i did not know how to fix it.please help me! THANK YOU in advance!

                close all;
                    clear all;
                    %
                    % PARAMETERS
                    %
                    freq = 200; %operating frequency
                    Fs = 20*f; %sampling frequency
                    L=100; % Number of samples per symbol period
                    Ts = 1/Fs; % Sampling period
                    T = Ts:Ts:1/f;
                    alpha=0.5; % Roll-off factor for the (square-root) raised cosine filters
                    N=8*L; % N+1 is the length of the square-root raised-cosine filter.
                    sigma_v=0; % Standard deviation of channel noise

                    h=1; % Channel impulse response
                    %
                    %SOURCE: Take input data from user for transmission
                    %
                    pt_dt = input('Data you want to send:','s');
                    R = isempty(pt_dt);
                    if R == 1
                    pt_dt = 'Waleed Ejaz';
                    else
                    pt_dt = pt_dt;
                    end
                    display(pt_dt);
                    RR = double(pt_dt);
                    bb = 1;
                    Rp = dec2bin(RR,7);
                    [TA TC] = size(Rp);
                    for ll = 1:1:TA
                    for lg = 1:1:TC
                    msg(bb) = Rp(ll,lg);
                    bb = bb + 1;
                    end
                    end
                    rt = 1; ht = 1;
                    for ls = 1:1:TA
                    for ll = 1:2:(TC-1)
                    Inp_msg(rt,(ht:ht+1)) = Rp(ls,(ll:ll+1));
                    rt = rt + 1;
                    end
                    end
                    %
                    % Transmit Filter
                    %
                    pT=f_sr_cos_p(N,L,alpha); % Transmit filter:
                    xT=conv(f_expander(msg,L),pT); % Transmit signal
                    %
                    % Modulation
                    %
                    display('Select Type of Modulation');
                    display('1. BPSK');
                    display('2. QPSK');
                    Mod_Type = input('Plz Enter the Type of Modulation:','s');
                    Carrier = [];
                    %
                    % BPSK Modulation
                    %
                    if (Mod_Type=='1')
                    display('Binary PSK');
                    for ii = 1:1:length(T)
                    car1(ii) = sin((2*pi*freq*T(ii))); %CARRIER TO BE TRANSMITTED
                    end
                    for ii = 1:1:length(xT)
                    if xT(ii) == '0'
                    car = -1*car1;
                    else
                    car = 1*car1;
                    end
                    Carrier = [Carrier car];
                    end
                    %
                    % QPSK Modulation
                    %
                    else if(Mod_Type=='2')
                    for ii = 1:1:length(T)
                    car1(ii) = sin((2*pi*freq*T(ii))+360); %CARRIER TO BE TRANSMITTED
                    car2(ii) = sin((2*pi*freq*T(ii))+90); %CARRIER TO BE TRANSMITTED
                    car3(ii) = sin((2*pi*freq*T(ii))+180); %CARRIER TO BE TRANSMITTED
                    car4(ii) = sin((2*pi*freq*T(ii))+270); %CARRIER TO BE TRANSMITTED
                    end
                    for ii = 1:1:length(Inp_msg)
                    if Inp_msg(ii) == '00'
                    car = car1;
                    else if Inp_msg(ii) == '01'
                    car = car2;
                    else if Inp_msg(ii) == '10'
                    car = car3;
                    else if Inp_msg(ii) == '11'
                    car = car4;
                    end
                    end
                    end
                    end
                    Carrier = [Carrier car];
                    end

                  if true
                    % code
                  end  end % end of if
                    end %end of else if
                    %

                  if true
                    % code
                  end
                    % CHANNEL
                    %
                    xR=conv(h,Carrier);

                  if true
                    % code
                  end
                    xR=xR+sigma_v*randn(size(xR)); % Received signal