Re: [eigen] again a unit test precision question

[joel falcou <joel.falcou@xxxxxx>]

Jitse Niesen wrote:
> On Sat, 3 Jul 2010, Hauke Heibel wrote:
>
> > Anyways, the redux_8 test is failing every now and then in redux.cpp
> > line 105 (e.g. seed 1278148098).
> >
> >
> > and it is failing with values
> >
> > 6.1214e-005 and 6.10948e-005
>
> The difference between these two values is 2e-7. The test adds 33 
> floats between -1 and 1. The error analysis for addition uses absolute 
> error, not relative error, so the correct test is whether
>
> abs(sum computed by one method - sum computed by another method) < 
> tolerance.
Could be better to measure error in ULP