| -----Original Message----- | From: boost-bounces@lists.boost.org | [mailto:boost-bounces@lists.boost.org] On Behalf Of John Maddock | Sent: 02 December 2005 17:25 | To: boost@lists.boost.org | Subject: Re: [boost] [math] floating point classification - | testinghelpwanted | | Actually if that's correct then things are a lot better than | I feared: the | text implies that the type behaves as a real type with | 106-bit's in the | significand. It also implies that numeric_limits<>::epsilon | must be buggy | for that platform. So I'm more confused than ever :-( If you want to be confused even further, attached is my inexpert stab at numeric_limits for NTL quad_float which I think may be the same. But I have asked the package author for his advice and help on this, but so far no reply (though there are regular package updates). I'm not sure that epsilon has a exactly defined value but I concluded static quad_float epsilon() throw() { return 2.4651903288156618919116517665087069677288E-32;}; // 2^(1-106) == 2^105 was my best guess. But without confirmation of this, in 'testing' NTL math functions, I cheated using the number of decimal digits quad_float tolpc = to_quad_float("1e-30"); // 31 guaranteed decimal digits, so percent tolerance is about 1e-29 BOOST_CHECK_CLOSE(x, one, tolpc); But I'm ready (anxious even) to have someone agree, or correct me. Paul -- Paul A Bristow Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB Phone and SMS text +44 1539 561830, Mobile and SMS text +44 7714 330204 mailto: pbristow@hetp.u-net.com http://www.hetp.u-net.com/index.html http://www.hetp.u-net.com/Paul%20A%20Bristow%20info.html