bugGNU Scientific Library - Bugs: bug #33679, gsl_sf_mathieu_se_array calculates...

 
 

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bug #33679: gsl_sf_mathieu_se_array calculates zeroth se as non-zero value

Submitter:  Nikolay Strelkov <nikolays>
Submitted:  Thu 30 Jun 2011 11:20:43 AM UTC
   
 
Category:  Runtime error Severity:  3 - Normal
Operating System:  Gentoo 10.0 amd64 Status:  Fixed
Assigned to:  None Open/Closed:  Closed
Release: 

Sun 24 Jul 2011 09:13:23 AM UTC, comment #5: 

Thank you!

Nikolay Strelkov <nikolays>
Thu 21 Jul 2011 04:07:22 PM UTC, comment #4: 

patch committed as revision 4740

-Deleted Account- <bjg>
Tue 05 Jul 2011 04:05:45 PM UTC, comment #3: 

I patched GSL 1.15 sources with your patch. It works as expected. The bug is FIXED. Thank you!

I hope this patch will be included in the next release.

Nikolay Strelkov <nikolays>
Tue 05 Jul 2011 03:23:21 PM UTC, comment #2: 

The attached patch should ensure that se_0(q,x) is always set to 0.

(file #23625)

Lowell D. Johnson <ldj>
Fri 01 Jul 2011 10:52:09 PM UTC, comment #1: 

Thanks for the report.  It will be sometime next week at the earliest before I'll have time to look into the issue, but wanted to at least acknowledge it.

Lowell D. Johnson <ldj>
Thu 30 Jun 2011 11:20:43 AM UTC, original submission:  

It is well known, that eigenvalue b0 for the odd solution b0 is not exist. Therefore the zeroth odd Mathieu function se is equal to zero.
In gsl_sf_mathieu_se you have check for trivial case where order=0. But there is no such check in gsl_sf_mathieu_se_array.

So gsl_sf_mathieu_se_array calculates se0 as non-zero.

I can illustrate my thoughts with simple example (gsl_se_test.c).
It calculates se functions for orders 0 and 1 with values of q=-10,0,10. The program calculates values with gsl_sf_mathieu_se and gsl_sf_mathieu_se_array. As you can see se0 values from array does not equal to zero:

q = -10.0
se_0 = 0.0000000000
se_0 = 0.6115006542 (from array)

q = 10.0
se_0 = 0.0000000000
se_0 = 0.6115006542 (from array)

P.S. I use GSL 1.15.

Nikolay Strelkov <nikolays>

 

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Attached Files
file #23625:  se_0.patch added by ldj (535B - text/x-patch)
file #23592:  gsl_se_test.c added by nikolays (865B - text/x-csrc - gsl_sf_mathieu_se_array and gsl_sf_mathieu_se test program)

 

Depends on the following items: None found

Items that depend on this one: None found

 

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  • -email is unavailable- added by ldj (Posted a comment)
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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2011-07-21 bjg StatusNone Fixed
        Open/ClosedOpen Closed
    2011-07-05 ldj Attached File- Added se_0.patch, #23625
    2011-06-30 nikolays Attached File- Added gsl_se_test.c, #23592

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