MATLAB: Am I getting this error, “Subscript indices must either be real positive integers or logicals.”

error message help

% This code worked the last time I ran it but now I get an error message. Why is this?
t = [-2: .001: 1.999];
mt = sinc(5 .* t ./ pi);
figure(1);
plot(t, mt);
xlabel('time');
ylabel('amplitude');
title('m(t)=sinc(5t/pi)');
grid;
PM = cos(50 .* pi + 20 .* mt);
figure(2);
plot(t, PM);
xlabel('time');
ylabel('amplitude');
title('PM Signal');
grid;
% cumsum function is used to calculate integral
integral_mt = cumsum(mt) .* 0.001;
FM = cos(50 .* pi + 40 .* pi .* integral_mt);
figure(3);
plot(t, FM);
xlabel('time');
ylabel('amplitude');
title('FM Signal');
grid;

Best Answer

Works for me. You probably defined a variable named sinc or plot or cos