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Re: odeiv_evolve_apply returns final value different than input
- From: Brian Gough <bjg at network-theory dot co dot uk>
- To: James <james dot umbanhowar at mcgill dot ca>
- Cc: gsl-discuss at sources dot redhat dot com
- Date: Sun, 17 Mar 2002 12:07:29 +0000 (GMT)
- Subject: Re: odeiv_evolve_apply returns final value different than input
- References: <3C939B58.9020201@mcgill.ca>
James writes:
> I'm trying to get evenly spaced samples from the adaptive step side
> integrator as suggested in the manual. however, the value t returned
> from gsl_odeiv_evolve_apply as the final value is 1x10-18 less than ti.
> I've developed an inelegant workaround but was wondering why this was
> happening? Is this a problem of different sized doubles?
It could be due to extended precsion, running the program with
GSL_IEEE_MODE=double-precision would show whether that was the case or
not.
Alternatively set a breakpoint in ode-initval/evolve.c and see what
happens to the variables 't' and 'final_step'.
Brian