Subscript ‘G’ to save it as a vector —
a=100.400;
b=230.033;
c1=1;
c2=4;
k=1:100;
for i =1:1:100
G(i)=1+c1*exp(-j*i*a)+c2*exp(-j*i*b);
end
figure
plot(real(G),k)
hold on
plot(imag(G),k)
hold off
grid
legend('Re','Im')
xlabel('G')
ylabel('k')
figure
plot(k,real(G))
hold on
plot(k,imag(G))
hold off
grid
legend('Re','Im')
xlabel('k')
ylabel('G')
Make appropriate changes to get the result you want.
.