I have a couple of feature requests for Boost.Test: 1) Can BOOST_CHECK_CLOSE please print the actual difference between the values (as a percent to match the tolerance) as well as the values themselves? The reason this is important, is that it's not always easy to get this value from the input values - because the precision of the machine on which the test is run far outstrips that of the author's machine, so his calculator isn't any use :-( 2) Can we please have a BOOST_CHECK_EPSILON, that uses a whole number of epsilon as the tolerance? IMO BOOST_CHECK_CLOSE should have been written this way to begin with, but it's too late now. Again it should print out the actual relative error as a multiple of epsilon as well as the input values. Actually while we're at it the absolute error may be useful to have in some situations as well :-) BTW, in case it helps: I've switched to using std::pow(two, 1-std::numeric_limits<T>::digits) to calculate machine epsilon, because of the strange behaviour on Darwin with long doubles if you use numeric_limits<>::epsilon() (see http://lists.boost.org/Archives/boost/2005/09/93390.php). Thanks! John.