From: jonathan <johnscpg@googlemail.com>
Subject: Re: matrix package with Ada
Date: Tue, 27 Jul 2010 15:10:10 -0700 (PDT)
Date: 2010-07-27T15:10:10-07:00 [thread overview]
Message-ID: <7594c659-3d67-427d-9c0e-10531d979fa0@e30g2000vbl.googlegroups.com> (raw)
In-Reply-To: af10bdc0-515e-4b17-a37c-47fa8809ff18@y11g2000yqm.googlegroups.com
I found another bug in Generic_Complex_Eigenvalues.
(From the collection at http://www.csee.umbc.edu/~squire/adaclass/gnatmath95/).
Wherever you find 2.0**( -23) in the code, it should be replaced
with Acc_Init, where
Acc_Init : constant Real := Real'Epsilon * 2.0**(-3);
-- 2**(-23) for digits 6, and 2**(-53) for digits 15, assuming usual
IEEE.
At the moment Generic_Complex_Eigenvalues only gives you single
precision
(digits 6), so it fails as a generic in the floating point type Real.
Also the program works poorly on matrices that are ill-conditioned,
and
it fails catastrophically on singular matrices. There is still
a large class of problems where it may be useful, but its limitations
should be loudly stated somewhere in .ads file.
J.
next prev parent reply other threads:[~2010-07-27 22:10 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-10 13:25 matrix package with Ada fitta
2010-07-10 13:46 ` MRE
2010-07-10 15:42 ` fitta
2010-07-10 18:34 ` tmoran
2010-07-10 18:54 ` Simon Wright
2010-07-10 20:23 ` Gautier write-only
2010-07-14 2:02 ` robin
2010-07-10 20:22 ` Gautier write-only
2010-07-12 1:58 ` Jerry
2010-07-12 13:38 ` Ada novice
2010-07-12 15:13 ` jonathan
2010-07-12 19:13 ` Ada novice
2010-07-12 20:13 ` Simon Wright
2010-07-12 21:09 ` jonathan
2010-07-13 7:07 ` Ada novice
2010-07-13 14:27 ` jonathan
[not found] ` <ec73f176-876e-4bcf-ab11-eed852129d34@x21g2000yqa.googlegroups.com>
2010-07-13 17:59 ` Jeffrey R. Carter
2010-07-13 18:00 ` Georg Bauhaus
2010-07-13 18:26 ` Ada novice
2010-07-19 22:34 ` Randy Brukardt
2010-07-20 7:27 ` Dmitry A. Kazakov
2010-07-25 19:15 ` Ada novice
[not found] ` <5f0082b8-7688-4422-be38-72f1c60be539@d8g2000yqf.googlegroups.com>
2010-07-25 19:39 ` Nasser M. Abbasi
2010-07-13 19:11 ` Simon Wright
2010-07-13 20:43 ` Ada novice
2010-07-14 18:55 ` Simon Wright
2010-07-12 20:59 ` Simon Wright
2010-07-13 16:40 ` Warren
2010-07-27 22:10 ` jonathan [this message]
2010-07-27 22:40 ` jonathan
2010-07-28 0:51 ` jonathan
2010-07-12 2:04 ` Jerry
2010-07-12 8:52 ` Ada novice
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