It shows File: mainvala.m Line: 77 Column: 21 Invalid use of operator. whenever i run this. Any fixexs?

%AMAN JAIN
%Ritwik Singh
%Arvindra kant nagar


clear
N = 10^6; % number of bits or symbols
EbN0dB = [0:25]; % multiple Eb/N0 values
nSym=128;
Tx = 2;
Rx = 2;
for ii = 1:length(EbN0dB) 
        % Transmitter
        ip = rand(1,nSym)>0.5; % generating 0,1 with equal probability
        s = 2*ip-1; % BPSK modulation 0 -> -1; 1 -> 0
        sMod = kron(s,ones(Rx,1)); % 
        sMod = reshape(sMod,[Rx,Tx,N/Tx]); % grouping in [nRx,nTx,N/NTx ] matrix
    
        h = 1/sqrt(2)*[randn(Rx,Tx,N/Tx) + j*randn(Rx,Tx,N/Tx)]; % Rayleigh fading
        n = 1/sqrt(2)*[randn(Rx,N/Tx) + j*randn(Rx,N/Tx)]; % white gaussian noise, 0dB variance
         
        % Channel and noise Noise addition
        y = squeeze(sum(h.*sMod,2)) + 10^(-EbN0dB(ii)/20)*n;  %adding channel trhrough which signal wil pass
        
        % Maximum Likelihood Receiver
        % ----------------------------
        % if [s1 s2 ] = [+1,+1 ]
        sout1 = [1 1];	
        sout1 = repmat(sout1,[1 ,N/2]); 
        sout1Mod = kron(sout1,ones(Rx,1));	
        sout1Mod = reshape(sout1Mod,[Rx,Tx,N/Tx]);	
        zsout1 = squeeze(sum(h.*sout1Mod,2)) ;
        J11 = sum(abs(y - zsout1),1);
        
        % if [s1 s2 ] = [+1,-1 ]
        sout2 = [1 -1];	
        sout2 = repmat(sout2,[1 ,N/2]);
        sout2Mod = kron(sout2,ones(Rx,1));	
        sout2Mod = reshape(sout2Mod,[Rx,Tx,N/Tx]);	
        zsout2 = squeeze(sum(h.*sout2Mod,2)) ;
        J10 = sum(abs(y - zsout2),1);
        
        % if [s1 s2 ] = [-1,+1 ]
        sout3 = [-1 1];	
        sout3 = repmat(sout3,[1 ,N/2]);
        sout3Mod = kron(sout3,ones(Rx,1));	
        sout3Mod = reshape(sout3Mod,[Rx,Tx,N/Tx]);	
        zsout3 = squeeze(sum(h.*sout3Mod,2)) ;
        J01 = sum(abs(y - zsout3),1);
        
        % if [s1 s2 ] = [-1,-1 ]
        sout4 = [-1 -1];	
        sout4 = repmat(sout4,[1 ,N/2]);
        sout4Mod = kron(sout4,ones(Rx,1));	
        sout4Mod = reshape(sout4Mod,[Rx,Tx,N/Tx]);	
        zsout4 = squeeze(sum(h.*sout4Mod,2)) ;
        J00 = sum(abs(y - zsout4),1);
        
        % finding the minimum from the four  combinations 
        rVec = [J11;J10;J01;J00];
        [jj dd] = min(rVec,[],1);
    
        % mapping the minima to bits
        ref = [1 1; 1 0; 0 1; 0 0 ];
        ipHat = zeros(1,N);
        ipHat(1:2:end) = ref(dd,1);
        ipHat(2:2:end) = ref(dd,2);
    
        % counting the errors
        nErr(ii) = size(find([ip- ipHat]),2);
end
%end
%end

simBer = nErr/N; % simulated ber
EbN0Lin = 10.^(EbN0dB/10);
theoryBer_nRx1 = 0.5.(1-1(1+1./EbN0Lin).^(-0.5)); 
p = 1/2 - 1/2.(1+1./EbN0Lin).^(-1/2);
theoryBerMRC_Rx2 = p.^2.(1+2(1-p)); 

close all

figure

semilogy(EbN0dB,theoryBer_nRx1,'g-O','LineWidth',2);

hold on
semilogy(EbN0dB,theoryBerMRC_Rx2,'kd-','LineWidth',2);
semilogy(EbN0dB,simBer,'--or','LineWidth',2);
axis([0 25 10^-5 0.5])
grid on
legend('theory (Tx=1,Rx=1)', 'theory (Tx=1,Rx=2, MRC)', 'sim (Tx=2, Rx=2, ML)');
xlabel('Average Eb/No,dB');
ylabel('Bit Error Rate');
title('BER VS SNR for 2x2 MIMO-OFDM-IM (Rayleigh channel)');

Answer 1

[Steven Lord]

Assuming the comment that starts your code is on line 1, lines 77-79 are:

theoryBer_nRx1 = 0.5.(1-1(1+1./EbN0Lin).^(-0.5)); 
p = 1/2 - 1/2.(1+1./EbN0Lin).^(-1/2);
theoryBerMRC_Rx2 = p.^2.(1+2(1-p)); 

You're missing operators after the first 0.5 on line 77, after the second 1/2 on line 78, and after both 2's on line 79.