Re: [Boost-users] Boost.Test: floating point comparison using absolute diference

Thank you. Is there a way to achieve this when comparing collections, i.e. when using boost::test_tools::per_element()?

On 29 Dec 2017, at 19:37, Raffi Enficiaud via Boost-users wrote:

Le 29.12.17 à 17:33, Georgios Sermaidis via Boost-users a écrit :

...

Hi all,

I am trying to find a way to make the boost unit test framework use an absolute difference for floating point comparison instead of the relative difference. I searched the documentation to try to find a suitable decorator but couldn’t find anything. Any help is much appreciated!

#defineBOOST_TEST_MODULEexample

#include

//boost::unit_test::toleranceusesrelativedifference and hence this test will pass;

// isthereanythingIcanusehereto indicateabsolutedifference?

BOOST_AUTO_TEST_CASE(my_test,*boost::unit_test::tolerance(0.1))

{

BOOST_TEST(10.1==10.3);

}

What you want to do is discussed here in the doc: http://www.boost.org/doc/libs/1_66_0/libs/test/doc/html/boost_test/testing_t...

You may just use

BOOST_TEST(left - right == .0, boost::unit_test::tolerance(0.1));

and I think it should use absolute tolerance on the absolute value of left-right.

If nothing works, there is always the good old comparison: BOOST_TEST((std::abs(left - right) < 0.1))

Note the double parenthesis, in this case BOOST_TEST will see only the evaluation of the expression inside, which is cast to bool (less elegant, but should work as last resort).

Raffi

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