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

[Pauli Virtanen]

Sun, 25 Jan 2009 20:03:26 +0100, Nils Wagner wrote:
> I do get three failures wrt. to special functions and python2.6

Too strict tolerances in the tests for the most part, I think. Will fix.
I presume this is a 64-bit Linux platform.

I'm in progress of addressing several bugs and improving the tests for 
the Bessel-related special functions in Scipy trunk. If someone wants to 
review the changesets I've committed recently, please go ahead.

> ======================================================================
> FAIL: test_yn_zeros (test_basic.TestBessel)
> ----------------------------------------------------------------------
[clip]
> Not equal to tolerance rtol=1e-19, atol=0

Too strict tolerance, I think. Some errors ~eps probably arise, depending 
on the compiler.

> ======================================================================
> FAIL: test_ynp_zeros (test_basic.TestBessel)
> ----------------------------------------------------------------------
[clip]
> AssertionError:
> Not equal to tolerance rtol=1e-07, atol=1e-15
> 
> (mismatch 100.0%)
>   x: array([  1.239e-10,  -8.119e-16,   3.608e-16, 5.898e-16,  
>   1.226e-15])
>   y: array(0)

Ditto. Except maybe for the first item. The question now is whether the 
problem is in the `yvp` routine or in `ynp_zeros`.

> ======================================================================
> FAIL: Negative-order Bessels
> ----------------------------------------------------------------------
[clip]
>      assert_tol_equal(iv(-0.5, 1   ), 1.231200214592967)
[clip]

Negative half-integers are a known failure of cephes/iv (also Scipy 
0.6.0), since hyperg has a pole at the corresponding points. But I think 
this test is commented out in the current SVN trunk, though.

I have a fix for this, but it's not committed yet. 

-- 
Pauli Virtanen