Regarding plot of cross correlation

Hi all, please check it out. It's urgent

I'm doing cross correlation of two column vector using xcorr() function. My code is

 time=data(:,1);
>> ux1=data(:,2);
>> ux2=data2(:,2);
>> cc=xcorr(ux1,ux2);
>> plot(time,cc);
it gives an error that vectors must be same length. then i did

>> n=length(time);
>> r=cc(1:n);
>> plot(time,r);
it does not gives a peak value, then i again did

>> plot(time,abs(r));
>> y=max(abs(r))

It gives the plot having one peak but I'm not sure that it is correct, becoz the time at peak value is not matching with my theoretical value.

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency

Answer 1

[Image Analyst]

Do this

length(time)  % No semicolon
length(cc) % No semicolon

and see what they print in the command window. They will be different lengths because the correlated signal's length is the sum of the two signals lengths minus 1. Try this:

plot(cc, 'bo-');

Why do you think there are more elements in cc than time? How do you think you need to construct a new time array so that it's the same length? What element of the new array corresponds to element 1 of the old time array? Maybe you should try some simple correlations by hand with like 5 elements and see what happens. It will be instructive.