April 2nd, 2009
Zion est un parc naturel américain situé au coeur de l’Utah:
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- Les photos n’ont pas été retouchées, la pierre est presque partout rougeâtre du à la nature ferrugineuse du sol.

- Un camping semi sauvage à l’entrée du Domaine du Parc


- Un conseil pour les photos du canyon : attendez le coucher du soleil, la lumière est beaucoup plus sympa…


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January 24th, 2009
Quand de nouveaux projets démarrent, on est parfois amenés à créer un document décrivant le design et les spécifications de ce dernier. Une question se pose alors : quelle terminologie utiliser ? Quelle sont les nuances de sens des verbes en Anglais ?
Je viens de dénicher une RFC décrivant cela, la RFC2119, très instructif :
Network Working Group S. Bradner
Request for Comments: 2119 Harvard University
BCP: 14 March 1997
Category: Best Current Practice
Key words for use in RFCs to Indicate Requirement Levels
Status of this Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Abstract
In many standards track documents several words are used to signify
the requirements in the specification. These words are often
capitalized. This document defines these words as they should be
interpreted in IETF documents. Authors who follow these guidelines
should incorporate this phrase near the beginning of their document:
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
RFC 2119.
Note that the force of these words is modified by the requirement
level of the document in which they are used.
1. MUST This word, or the terms "REQUIRED" or "SHALL", mean that the
definition is an absolute requirement of the specification.
2. MUST NOT This phrase, or the phrase "SHALL NOT", mean that the
definition is an absolute prohibition of the specification.
3. SHOULD This word, or the adjective "RECOMMENDED", mean that there
may exist valid reasons in particular circumstances to ignore a
particular item, but the full implications must be understood and
carefully weighed before choosing a different course.
4. SHOULD NOT This phrase, or the phrase "NOT RECOMMENDED" mean that
there may exist valid reasons in particular circumstances when the
particular behavior is acceptable or even useful, but the full
implications should be understood and the case carefully weighed
before implementing any behavior described with this label.
5. MAY This word, or the adjective "OPTIONAL", mean that an item is
truly optional. One vendor may choose to include the item because a
particular marketplace requires it or because the vendor feels that
it enhances the product while another vendor may omit the same item.
An implementation which does not include a particular option MUST be
prepared to interoperate with another implementation which does
include the option, though perhaps with reduced functionality. In the
same vein an implementation which does include a particular option
MUST be prepared to interoperate with another implementation which
does not include the option (except, of course, for the feature the
option provides.)
6. Guidance in the use of these Imperatives
Imperatives of the type defined in this memo must be used with care
and sparingly. In particular, they MUST only be used where it is
actually required for interoperation or to limit behavior which has
potential for causing harm (e.g., limiting retransmisssions) For
example, they must not be used to try to impose a particular method
on implementors where the method is not required for
interoperability.
7. Security Considerations
These terms are frequently used to specify behavior with security
implications. The effects on security of not implementing a MUST or
SHOULD, or doing something the specification says MUST NOT or SHOULD
NOT be done may be very subtle. Document authors should take the time
to elaborate the security implications of not following
recommendations or requirements as most implementors will not have
had the benefit of the experience and discussion that produced the
specification.
8. Acknowledgments
The definitions of these terms are an amalgam of definitions taken
from a number of RFCs. In addition, suggestions have been
incorporated from a number of people including Robert Ullmann, Thomas
Narten, Neal McBurnett, and Robert Elz.
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January 9th, 2009
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January 8th, 2009
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December 23rd, 2008
Most people know that Descarte said, “I think, therefore I am.” What most people don’t know is that that quote continues, “…afraid of Chuck Norris.“
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December 20th, 2008
L’analyse par régression est une technique très utilisée dans la vie quotidienne de l’ingénieur :
Voici quelques notes qui peuvent être utiles pour quiconque veut se lancer dans l’analyse corrélative :
Quelques notations :
- Matrice des covariances
L’ensemble des M observations d’un couple de variables peut être mis sous la forme d’une matrice d’observation X :
On peut donc créer la matrice de la somme des carrés :
avec :
On peut ensuite construire la matrice de la somme des carrés des écarts :
2. Matrice de corrélation
La matrice de corrélation correspond à la normalisation de la matrice de covariance :
Plus à venir d’ici peu
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December 20th, 2008
Les standards de code sont importants à respecter dans tout projet digne de ce nom. Google propose un guide de style pour le code C++ :
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml
Enjoy !
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December 19th, 2008
Ma passion pour le traitement du signal ne désemplit pas
:
http://www.polytech.unice.fr/~leroux/
Au menu :
- Base des probabilités appliquées au traitement du signal
- Le traitement numérique du signal
- Modèles de Markov cachés
- Traitement du signal bidimensionnel (image)
- Estimation récursive (commande, estimation, filtrage de Kalman)
Bref, tout ce qu’il faut retenir après un cursus UTC STRIE ou presque… On regrettera peut etre juste une introduction à la théorie des Ondelettes.
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December 18th, 2008
Une petite piqûre de rappel sur un texte qu’on oublie trop souvent (extrait) :

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December 18th, 2008
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