How to plot a PCM graph

Hello,

I have tried to run a MP3 decoder coding which is obtained from this link http://se.mathworks.com/matlabcentral/fileexchange/27303-complete-implementation-of-a-mp3-decoder. I want to plot a PCM graph, so I add a few lines of code before the ending.

    plot(1/frequency,out_PCM_samples);
    title('PCM waveform');
  end

However, there was error showing : Vectors must be the same lengths. May I know what is the problem and the solution for plotting a PCM graph?

Thank you.