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From: FEVOTTE F. <fra...@ed...> - 2017-06-02 13:21:45
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Le jeudi 01 juin 2017 à 13:46 +0200, Roland Mainz a écrit : > It would be nice to be able to "define" the randomness here, e.g. by > providing a pseudo-random-number generator and a command line option > to provide the "seed" value. We are planning to add a command-line switch to provide the seed value (https://github.com/edf-hpc/verrou/issues/3), but I don't think that we will go any further than that. In other words, we don't plan changing the pRNG nor letting the user define it. > Point is that you can actually debug > issues in a deterministic&&repeatable way *IF* they happen. In order to have a deterministic way to perturb results, we have a "farthest" rounding mode, which always rounds in an opposite way to the standard nearest rounding mode (it leaves representable values unchanged, though). This is documented here: http://edf-hpc.github.io/verrou/vr-manual.html#vr-manual.feat.rounding-mode > Another issue is to make sure things like +nan/-nan and NaNs with > payloads work correctly with your tool since there are lots of > applications which use this kind of stuff for error ("error" as in > "error message") propagation. This is a very good point, thanks! I just checked and it appears that Verrou currently preserves NaN values, but sometimes changes an infinite value into a (large but) finite one. Also, NaN payloads are sometimes changed. So there is some work to do here. I opened an issue to handle this: https://github.com/edf-hpc/verrou/issues/4 Thanks for your comment, François -- François FÉVOTTE Research Engineer EDF – R&D – PERICLES I23 (Analysis and Numerical Modeling) 7 boulevard Gaspard Monge 91120 Palaiseau - FRANCE fra...@ed... Phone: +33 1 78 19 44 23 Ce message et toutes les pièces jointes (ci-après le 'Message') sont établis à l'intention exclusive des destinataires et les informations qui y figurent sont strictement confidentielles. Toute utilisation de ce Message non conforme à sa destination, toute diffusion ou toute publication totale ou partielle, est interdite sauf autorisation expresse. Si vous n'êtes pas le destinataire de ce Message, il vous est interdit de le copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou partie. Si vous avez reçu ce Message par erreur, merci de le supprimer de votre système, ainsi que toutes ses copies, et de n'en garder aucune trace sur quelque support que ce soit. Nous vous remercions également d'en avertir immédiatement l'expéditeur par retour du message. Il est impossible de garantir que les communications par messagerie électronique arrivent en temps utile, sont sécurisées ou dénuées de toute erreur ou virus. ____________________________________________________ This message and any attachments (the 'Message') are intended solely for the addressees. The information contained in this Message is confidential. Any use of information contained in this Message not in accord with its purpose, any dissemination or disclosure, either whole or partial, is prohibited except formal approval. If you are not the addressee, you may not copy, forward, disclose or use any part of it. If you have received this message in error, please delete it and all copies from your system and notify the sender immediately by return message. E-mail communication cannot be guaranteed to be timely secure, error or virus-free. |