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From: Beman Dawes (bdawes_at_[hidden])
Date: 2003-07-07 15:05:05

At 02:22 PM 7/7/2003, Rozental, Gennadiy wrote:

>I could probably prohibit usage of CHECK_CLOSE with number of rounding
>errors provided.
>Is there any other general recommendations how to choose the tolerance to

>FP computation correctness checking?

There has been some recent discussion on comp.lang.c++.moderated, subject
"equality of two doubles". The last post was from Andrei Alexandrescu:

>What's most of the time needed is relative precision.
>So, numerical gurus: how can one express "a equals b within 0.1%" over
>the whole range of floating point numbers? If that can be done, it would
>be a nice useful routine.
>bool approximately_equal(double lhs, double rhs, double relative_prec)
> // fill in here please :o)

But it really doesn't seem that a test library is the right home for such
functions. I think all the fp stuff should be removed from Boost.Test, and
passed on as a challenge to the numerics experts.

After all, the user can always write:

   BOOST_CHECK( approximately_equal(...) );


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