what is practical importance of cross correlation suppose if we corelate two discreate sequences {1, 2 ,3} and {2 , 0 ,5} the answer is { 5 10 17 4 6}
what does there value shows high correlation , low correlation or anyother
A non-mathematician way to look at cross-correlation is the misnomer 'pattern matching'. I had to use cross-correlation to pick a pleth (heart-beat) pattern out of a raw ECG signal.
Also, arguably, an FT or FFT is cross-correlation of the input with a sine wave of a given frequency. (Also, do it with the cosine-wave of each frequency and you remove the phase sensitivity.) The complexity comes from the tricks used to speed up the process.
I struggled with FFTs for a long time before someone ( a P.H.D in DSP of all people) explained that to me.