Re: [task #7793] Speed-up of dispersion models -- May 28, 2014 - 12:24

Hi Edward.

The NS CPMG 2site extended is a good case.

It will make a underflow for kex as low as 1e4.

  File 
"/Users/tlinnet/software/disp_speed/test_suite/unit_tests/_lib/_dispersion/test_ns_cpmg_2site_expanded.py",
line 180, in test_ns_cpmg_2site_expanded_no_rex8
    self.calc_r2eff()
  File 
"/Users/tlinnet/software/disp_speed/test_suite/unit_tests/_lib/_dispersion/test_ns_cpmg_2site_expanded.py",
line 58, in calc_r2eff
    R2eff = r2eff_ns_cpmg_2site_expanded(r20=self.r20, pA=self.pA,
dw=dw_frq, k_AB=k_AB, k_BA=k_BA, relax_time=0.3, inv_relax_time=1/0.3,
tcp=self.tcp, num_points=self.num_points, num_cpmg=self.num_cpmg)
  File 
"/Users/tlinnet/software/disp_speed/lib/dispersion/ns_cpmg_2site_expanded.py",
line 298, in r2eff_ns_cpmg_2site_expanded
    t28 = exp(-(t17 + k_AB_plus_k_BA_minus_t4) * half_tcp)
FloatingPointError: underflow encountered in exp

And, the test is extremely fast. So I would rather keep it, as a last
line of defence.

Best
Troels

2014-05-28 12:10 GMT+02:00 Edward d'Auvergne <edward@xxxxxxxxxxxxx>:
> Hi,
>
> Do you have an example where infinite or NaN values appear?  I think
> that with the 'No Rex' checks, we now 100% avoid these.  So I believe
> that all Inf and NaN values came from the parameter values dw == 0.0
> or pA == 1.0 or kex == 0.0 or phi_ex = 0.0 causing a failure in the
> original dispersion equations.  That is what this patch demonstrates -
> for all cases in the test suite, there is no longer any Inf or NaN
> values :)  At least for the models we check for no exchange
> conditions.
>
> Regards,
>
> Edward
>
>
>
>
>
> On 28 May 2014 12:01, Troels Emtekær Linnet <tlinnet@xxxxxxxxxxxxx> wrote:
> > Hi Edward.
> >
> > I cannot accept the patch.
> >
> > It removes all the isfinite(sum(R1rho)) tests I have put in.
> >
> > Best
> > Troels
> >
> >
> > 2014-05-28 11:53 GMT+02:00 Edward d  Auvergne
> > <NO-REPLY.INVALID-ADDRESS@xxxxxxx>:
> > > Follow-up Comment #86, task #7793 (project relax):
> > >
> > > I have modified the patch for the latest version of the disp_speed branch
> > > (r23503).
> > >
> > > (file #20827)
> > >     _______________________________________________________
> > >
> > > Additional Item Attachment:
> > >
> > > File name: patch_check_removal2           Size:10 KB
> > >
> > >
> > >     _______________________________________________________
> > >
> > > Reply to this item at:
> > >
> > >   <http://gna.org/task/?7793>
> > >
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