I am currently looking at various elliptical Copula models and was wondering if anyone knows what the general practices are to calculate the correlation matrix within the copula joint distribution (i.e. input to the cholesky decompositon within the copula algorithm) e.g. say we have two reference entities A and B which are correlated (to keep it simple assume this is independent form treasury rate etc) and we have the correlation matrix:1 ññ 1How do we determine ñ (as a side questions is it possible to backout ñ if you have a time series of the credit spread values for A and B)Any suggestions would be appriciated - thanks