Real-time graph with multiple data from Arduino

Hi,

I am streaming data from an Arduino to the USB and plotting it in Matlab in real time. It works fine with a single stream of numbers but I can't get it to work with 3 sets of data.

I am currently streaming eg

3
6
2
9
6
etc

but when I go to eg

5 4 3
2 4 1 
8 3 5
7 6 4
etc and try to call out the 3 columns I can't get it to work. I can configure the Arduino data to stream any way suitable if need be.

Any advise welcome

Philip

current code;

(My code was adapted from http://lungfulcoding.blogspot.co.uk/2013/03/basic-arduino-and-matlab-setup.html)

%

make sure no old serial ports are open
clear
delete(instrfindall);

%connect to serial port and set baud rate
s1 = serial('com7','BaudRate', 9600);
% open connection and send identification (to initalize it or something???)
fopen(s1);
fprintf(s1, '*IDN?');
%number of points to be plotted
numberOfPoints = 200;
%initialize with zeros, to hold yvalues
%yVal0(1:numberOfPoints)= 0;
yVal1(1:numberOfPoints)= 0;
yVal2(1:numberOfPoints)= 0;
yVal3(1:numberOfPoints)= 0;
% x axis points
xVal = (1:numberOfPoints);
%create an empty plot
thePlot = plot(nan);
%delay or pause so serial data doesnt stutter
pause(1);
hold on
for index = (1:numberOfPoints)
    %reading value from Arduino
    yVal(index) = 50*str2double(fgets(s1));
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % this section is wrong at the moment, I am trying to split yval into 4
    % and then plot n as channel 0, n+1 as channel 1, n+2 etc

n = 4;
yVal0 = yVal(1 : n : end);  % => 1 5 9
yVal1 = yVal(2 : n : end);  % => 2 6 10
yVal2 = yVal(3 : n : end);  % => 3 7 11
yVal3 = yVal(4 : n : end);  % => 4 8 12    

      %every 100 points, plot the entire graph
      if mod(index,10) == 0
          set(thePlot,'YData',yVal0, 'XData', xVal);
           set(thePlot,'YData',yVal1, 'XData', xVal);
           set(thePlot,'YData',yVal2, 'XData', xVal);
           set(thePlot,'YData',yVal3, 'XData', xVal);
          drawnow
      end
  end

hold off
%close the port and delete it
fclose(s1);
delete(s1)
clear('s1')
delete(instrfindall)