[SciPy-dev] FAIL: test_yn_zeros, test_ynp_zeros, Negative-order Bessels

Pauli Virtanen pav@iki...
Mon Jan 26 03:28:47 CST 2009

Mon, 26 Jan 2009 09:03:19 +0100, Nils Wagner wrote:
> ======================================================================
> FAIL: test_iv_cephes_vs_amos (test_basic.TestBessel)
> ----------------------------------------------------------------------
> Not equal to tolerance rtol=1e-08, atol=1e-305 (-120, -11)
> (mismatch 100.0%)
>   x: array(1.3384173609003782e-110)
>   y: array((1.3384173859242368e-110+0j))

The way cephes/iv computes the value of Iv is not too accurate for large 
orders or large x. I have some code to compute the result in this range 
from proper asymptotic expansions, but also it isn't committed yet.

Pauli Virtanen

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