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Re: Bug in Jacobi elliptic functions


Ivan E. Panchenko writes:
 > There is a bug, probably in the algorithm itself.
 > When one calculates dn(x) by  gsl_sf_elljac_impl at _exactly_
 > one half of its period, dn(0) is returned instead. 

Thanks for the bug report -- stepping through the code shows that the
algorithm suffers from loss of precision at that point due to
cancellation errors.  Jerry, is there some way to avoid this?


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