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Re: negative absolute error given by qag?


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


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