Looking for an algorithm that computes "Similarity" between two signals I'm new in this forum! ... and I'm not an expert in signal processing! ... So I hope to find help here:-)
I was wondering if someone could point me to an algorithm/technique that is used to compare time dependent signals. Ideally, this hypothetical algorithm would take in 2 signals as inputs and return a number that would be the percentage similarity between the signals.
In other terms I’m looking for a technique that allows to establish a degree of “similarity” between the two signals even if there is a delay or a shift between them. Obviously, if this technique could be implemented in a recursive way or with a small number of point ...it would be great! :-) 

Thanks
Coherence? As in: http://en.wikipedia.org/wiki/Coherence_(signal_processing). By comparing the signal spectrums, you get real number numbers between 0 and 1, which each number is a measure of the similarity of the two signals at each frequency.  But it might be difficult for a beginner to understand and program.  You might look for simpler explanations and/or examples by doing a Google search for 'signal coherence', which results in about 17 million hits.