We are currently looking for volunteers that would like to contribute to
the Dionysus project. In particular, we are looking for people that would
like to insert new constants in the database. Everybody is very welcome!
If you are interested, please contact jeanmichel [dot] sellier [at] gmail
Introduction to Dionysus
Dionysus is a local machine search engine for universal constants and
parameters of scientific and engineering relevance. If you develop a code
and need any kind of well known constant you do not need to hard code them
anymore. Just use Dionysus and it will do the job for you.
Dionysus is also useful if you need to know some well known constant but you
do not have an Internet connection or you do not want to access to hundreds
web pages to a simple value.
Dionysus has been developed as most carefully as possible and the author
expects the package to be reliable for the plenty of values already included
Anytime you need a value, do not hard code it. Just ask Dionysus and it will
give you the right answer. It is high consuming to look for parameters
values, especially because those values are usually scattered among papers
and websites, some of them being very old and/or impossible to find
can be found on the main GNU ftp server:
(via HTTP) and
(via FTP). It can also be found
on the GNU mirrors;
a mirror if possible.
Let us suppose one wants to know the value of the elementary charge (i.e.
the absolute value of the electron charge). One has several ways of finding
- going to a library and look for that constant in a book
- browsing the web pages to find it
- asking Dionysus!!
The third way is actually the easiest!
Usually, this constant is denoted by the letter "e" (among engineers) or by
the letter "q" (among physicists). So, one can ask Dionysus the exact value
by typing one of the following commands:
> dionysus universal.ddb elementary_charge value
> dionysus universal.ddb q value
> dionysus universal.ddb e value
where "universal.ddb" is a database ASCII file provided along with the
current version. The value returned is:
It's REALLY easy like that! And you can ask much more than that to Dionysus!
Databases in the current version
The current version of Dionysus provides three databases:
which contains the value of 46 well-known universal constants.
which contains the atomic number of 104 chemical elements.
which contains 40 semiconductors constants.
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Dionysus is a GNU package mainly developed by Jean Michel Sellier. If you
have any request or suggestion about this package you are very welcome. You
can send them to:
jeanmichel [dot] sellier [at] gmail [dot] com
is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free
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