% Fig. 3-5; Bit error probabilities for binary signaling;
% a vector of correlation coefficients between signals is allowed
%
clf
R12 = input('Enter vector of desired R_1_2 values; maximum of 4 ');
A = char('-','-.',':','--');
k=1;
LR = length(R12);
z_dB = 0:.3:15;             % Vector of desired values of Eb/N0 in dB
z = 10.^(z_dB/10);
for k = 1:LR                % Loop for various values of R12
    P_E=qfn(sqrt(z*(1-R12(k))));
    semilogy(z_dB,P_E,A(k,:)),axis([0 15 10^(-6) 1]),xlabel('E_b/N_0, dB'),ylabel('P_b'),...
        title('Bit error probability for binary signaling with correlation R_1_2 between signals')
    if k==1
        hold on
        grid
    end
end
% Put appropriate legend on graph, depending on number of R12 values chosen
if LR == 1
    legend(['R_1_2 = ',num2str(R12(1))],1)
elseif LR == 2
    legend(['R_1_2 = ',num2str(R12(1))],['R_1_2 = ',num2str(R12(2))],1)
elseif LR == 3
    legend(['R_1_2 = ',num2str(R12(1))],['R_1_2 = ',num2str(R12(2))],['R_1_2 = ',num2str(R12(3))],1)
elseif LR == 4
    legend(['R_1_2 = ',num2str(R12(1))],['R_1_2 = ',num2str(R12(2))],['R_1_2 = ',num2str(R12(3))],['R_1_2 = ',num2str(R12(4))],1)
end