Error using EMD function

Dear all, I am new to Matlab, i want to use the function EMD for the database physionet MIH-BIH

for this example: ----------------------------------------------------- load('sinusoidalSignalExampleData.mat','X','fs'); t = (0:length(X)-1)/fs; plot(t,X); xlabel('Time(s)'); %[imf,residual,info] = emd(X,'Interpolation','pchip'); [imf,info] = emd(X); ------------------------------------------------------ please, I need help to know the 'X' value what does means!!, in order to use it for database physionet MIH-BIH

Thank you so much in advance. Kind regards,