[Perldl] cspline does not extrapolate?

Chris Marshall devel.chm.01 at gmail.com
Fri Feb 10 04:51:28 HST 2012


I cannot reproduce the problem with cygwin PDL-2.4.10
but the win32 PDL-2.4.10 give NaNs for the extrapolated
values.

InSuk, please update the bug ticket on sf.net with your
perl -V and perldl -V information.

Thanks,
Chris

On Fri, Feb 10, 2012 at 9:26 AM, Chris Marshall <devel.chm.01 at gmail.com> wrote:
> I ran a C version of the example and it worked
> and gave -1 for the value.  I'll cook up a simple
> test case to add to our test suite for use in
> debugging the problem.  If you see what is wrong
> with the current gsl_interp.pd code, patches are
> definitely welcome---and get fixes released
> sooner.
>
> Thanks for the report,
> Chris
>
>
> On Thu, Feb 9, 2012 at 8:16 PM, chm <devel.chm.01 at gmail.com> wrote:
>> Hmm.  Ok.  So much for the quick fix.
>>
>> I did not think that a cspline fit was
>> valid for the GSL interp eval routine.
>> I guess someone who can check against the
>> actual GSL interp routine results can show
>> what the correct value should be.
>>
>> Sorry I couldn't be more helpful.
>>
>> --Chris
>>
>>
>> On 2/9/2012 7:57 PM, InSuk Joung wrote:
>>>
>>> Hi,
>>> Thank you for the reply. Anyway, it should not be an exception. The
>>> correct
>>> answer of the test code should be -1 not nan. At least, that's the number
>>> I
>>> get from v2.4.6.
>>>
>>> On Thu, Feb 9, 2012 at 7:37 PM, chm<devel.chm.01 at gmail.com>  wrote:
>>>
>>>> On 2/9/2012 6:01 PM, InSuk Joung wrote:
>>>>
>>>>> use strict;
>>>>> use warnings;
>>>>> use PDL;
>>>>> use PDL::GSL::INTERP;
>>>>>
>>>>> my $x = sequence(10);
>>>>> my $y = $x**2;
>>>>>
>>>>> my $spl = PDL::GSL::INTERP->init( 'cspline', $x, $y );
>>>>> print $spl->eval( -1, {Extrapolate=>1} ), "\n";
>>>>>
>>>>
>>>> The problem with the exception handler appears
>>>> to have been fixed since the PDL-2.4.7 release
>>>> (according to the git log).  To avoid the problem
>>>> you'll need to avoid out-of-domain values for the
>>>> input parameter being evaluated or switch to PDL
>>>> version 2.4.8 or newer (the PDL-2.4.10 release
>>>> this week has many bugs fixed and new features!).
>>>> I ran your test code on 2.4.10 and the result
>>>> was nan with no error as expected.
>>>>
>>>> --Chris
>>>>
>>>
>>>
>>>
>>




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