* negative absolute error given by qag?
@ 2002-12-31 9:55 Francisco J Molina
2002-04-30 18:07 ` Francisco J Molina
2002-12-31 9:55 ` Brian Gough
0 siblings, 2 replies; 8+ messages in thread
From: Francisco J Molina @ 2002-12-31 9:55 UTC (permalink / raw)
To: gsl-discuss, fjmolina
I am using the function
gsl_integration_qag
Is it possible that this function returns an absolute error ( abserr )
that is negative.
I have been reading the code of qag.c and that seems to be the case.
Anyone could confirm this?
^ permalink raw reply [flat|nested] 8+ messages in thread
* negative absolute error given by qag?
2002-12-31 9:55 negative absolute error given by qag? Francisco J Molina
@ 2002-04-30 18:07 ` Francisco J Molina
2002-12-31 9:55 ` Brian Gough
1 sibling, 0 replies; 8+ messages in thread
From: Francisco J Molina @ 2002-04-30 18:07 UTC (permalink / raw)
To: gsl-discuss, fjmolina
I am using the function
gsl_integration_qag
Is it possible that this function returns an absolute error ( abserr )
that is negative.
I have been reading the code of qag.c and that seems to be the case.
Anyone could confirm this?
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: negative absolute error given by qag?
2002-12-31 9:55 negative absolute error given by qag? Francisco J Molina
2002-04-30 18:07 ` Francisco J Molina
@ 2002-12-31 9:55 ` Brian Gough
2002-05-01 16:41 ` Brian Gough
2002-12-31 9:55 ` Francisco J Molina
1 sibling, 2 replies; 8+ messages in thread
From: Brian Gough @ 2002-12-31 9:55 UTC (permalink / raw)
To: Francisco J Molina; +Cc: gsl-discuss, fjmolina
Francisco J Molina writes:
> I am using the function
> gsl_integration_qag
> Is it possible that this function returns an absolute error (
> abserr ) that is negative.
> I have been reading the code of qag.c and that seems to be the
> case.
> Anyone could confirm this?
Hi,
Negative errors shouldn't occur under normal usage, so if you
encounter any negative errors please send a bug report. Thanks.
> How can I avoid a message of this type:
> gsl: qag.c:257: ERROR: maximum number of subdivisions reached
> I am know in the world of C++. Does anyone which is the basic tool
> in C++ to handle exceptions/errors?
You can use the function gsl_set_error_handler_off() at the beginning
of your program, and then the return status of gsl functions for
errors.
regards
Brian Gough
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: negative absolute error given by qag?
2002-12-31 9:55 ` Brian Gough
@ 2002-05-01 16:41 ` Brian Gough
2002-12-31 9:55 ` Francisco J Molina
1 sibling, 0 replies; 8+ messages in thread
From: Brian Gough @ 2002-05-01 16:41 UTC (permalink / raw)
To: Francisco J Molina; +Cc: gsl-discuss, fjmolina
Francisco J Molina writes:
> I am using the function
> gsl_integration_qag
> Is it possible that this function returns an absolute error (
> abserr ) that is negative.
> I have been reading the code of qag.c and that seems to be the
> case.
> Anyone could confirm this?
Hi,
Negative errors shouldn't occur under normal usage, so if you
encounter any negative errors please send a bug report. Thanks.
> How can I avoid a message of this type:
> gsl: qag.c:257: ERROR: maximum number of subdivisions reached
> I am know in the world of C++. Does anyone which is the basic tool
> in C++ to handle exceptions/errors?
You can use the function gsl_set_error_handler_off() at the beginning
of your program, and then the return status of gsl functions for
errors.
regards
Brian Gough
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: negative absolute error given by qag?
2002-12-31 9:55 ` Brian Gough
2002-05-01 16:41 ` Brian Gough
@ 2002-12-31 9:55 ` Francisco J Molina
2002-05-01 17:28 ` Francisco J Molina
2002-12-31 9:55 ` Brian Gough
1 sibling, 2 replies; 8+ messages in thread
From: Francisco J Molina @ 2002-12-31 9:55 UTC (permalink / raw)
To: Brian Gough, gsl-discuss
Brian Gough wrote:
>
> Francisco J Molina writes:
> > I am using the function
> > gsl_integration_qag
> > Is it possible that this function returns an absolute error (
> > abserr ) that is negative.
> > I have been reading the code of qag.c and that seems to be the
> > case.
> > Anyone could confirm this?
>
It was my mistake. Negative errors are not occuring when I use qag.
Do you know how I can avoid the error:
roundoff error prevents tolerance from being achieved?
> Hi,
>
> Negative errors shouldn't occur under normal usage, so if you
> encounter any negative errors please send a bug report. Thanks.
>
> > How can I avoid a message of this type:
> > gsl: qag.c:257: ERROR: maximum number of subdivisions reached
> > I am know in the world of C++. Does anyone which is the basic tool
> > in C++ to handle exceptions/errors?
>
> You can use the function gsl_set_error_handler_off() at the beginning
> of your program, and then the return status of gsl functions for
> errors.
>
> regards
> Brian Gough
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: negative absolute error given by qag?
2002-12-31 9:55 ` Francisco J Molina
@ 2002-05-01 17:28 ` Francisco J Molina
2002-12-31 9:55 ` Brian Gough
1 sibling, 0 replies; 8+ messages in thread
From: Francisco J Molina @ 2002-05-01 17:28 UTC (permalink / raw)
To: Brian Gough, gsl-discuss
Brian Gough wrote:
>
> Francisco J Molina writes:
> > I am using the function
> > gsl_integration_qag
> > Is it possible that this function returns an absolute error (
> > abserr ) that is negative.
> > I have been reading the code of qag.c and that seems to be the
> > case.
> > Anyone could confirm this?
>
It was my mistake. Negative errors are not occuring when I use qag.
Do you know how I can avoid the error:
roundoff error prevents tolerance from being achieved?
> Hi,
>
> Negative errors shouldn't occur under normal usage, so if you
> encounter any negative errors please send a bug report. Thanks.
>
> > How can I avoid a message of this type:
> > gsl: qag.c:257: ERROR: maximum number of subdivisions reached
> > I am know in the world of C++. Does anyone which is the basic tool
> > in C++ to handle exceptions/errors?
>
> You can use the function gsl_set_error_handler_off() at the beginning
> of your program, and then the return status of gsl functions for
> errors.
>
> regards
> Brian Gough
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: negative absolute error given by qag?
2002-12-31 9:55 ` Francisco J Molina
2002-05-01 17:28 ` Francisco J Molina
@ 2002-12-31 9:55 ` Brian Gough
2002-05-03 11:33 ` Brian Gough
1 sibling, 1 reply; 8+ messages in thread
From: Brian Gough @ 2002-12-31 9:55 UTC (permalink / raw)
To: Francisco J Molina; +Cc: gsl-discuss
Francisco J Molina writes:
> Do you know how I can avoid the error:
>
> roundoff error prevents tolerance from being achieved?
Hi,
Some strategies for difficult integrals are discussed in the QUADPACK
manual (referenced in the GSL integration chapter). Usually it comes
down to rewriting the integral to reduce numerical cancellations.
regards
Brian
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: negative absolute error given by qag?
2002-12-31 9:55 ` Brian Gough
@ 2002-05-03 11:33 ` Brian Gough
0 siblings, 0 replies; 8+ messages in thread
From: Brian Gough @ 2002-05-03 11:33 UTC (permalink / raw)
To: Francisco J Molina; +Cc: gsl-discuss
Francisco J Molina writes:
> Do you know how I can avoid the error:
>
> roundoff error prevents tolerance from being achieved?
Hi,
Some strategies for difficult integrals are discussed in the QUADPACK
manual (referenced in the GSL integration chapter). Usually it comes
down to rewriting the integral to reduce numerical cancellations.
regards
Brian
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2002-05-03 18:33 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2002-12-31 9:55 negative absolute error given by qag? Francisco J Molina
2002-04-30 18:07 ` Francisco J Molina
2002-12-31 9:55 ` Brian Gough
2002-05-01 16:41 ` Brian Gough
2002-12-31 9:55 ` Francisco J Molina
2002-05-01 17:28 ` Francisco J Molina
2002-12-31 9:55 ` Brian Gough
2002-05-03 11:33 ` Brian Gough
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