From my understanding of the problem, it sounds like you would like to determine the correlation between a given wavelet and the mother wavelet. Have you tried to use "wavefun" to generate the mother wavelet as a separate signal and then pass that to "wcoher"? One of the output arguments of "wcoher", called "xval", can be used to evaluate your signal such that the sizes are consistent when passed to "wcoher". "wcoher" ends up using "wavefun" to evaluate the wave you specify in 'wname' so this might give the desired result. For more information, please see:
Please let me know if I misunderstood your question.
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