Version numbers, & why they change

There are three reasons. 1) The numerical methods improve with time, as computers grow ever faster. Today's answer is more sophisticated. 2) The atomic data base is exploding, both in quality and quantity. The cross sections and rate coefficients are much better. 3) Anything as complex as Cloudy contains bugs, which are fixed as soon as they are discovered.

Cloudy uses version numbers to keep track of changes to the code: Cloudy uses version numbers to keep track of changes to the code: There are usually three versions of the code in Lexington. The most stable is the current "gold" version (now C94). A "beta" version will exist and is a (pretty) well tested of the next version. Finally there is a development version which may have some spectacular bugs. Major upgrades to gold versions occur on a 3 year basis and are available through this web site. These are released only every few years, because it takes many months of testing, on as many platforms as possible, to validate a gold version. Minor changes to the gold version occur from time to time, usually to fix problems as they are discovered.

Major Changes: These are indicated by integer increments to the version number. The current gold version is 94, and was released on Dec 24 of 1999. The previous gold version was 90, released on June 17, 1996.
Minor changes: These are indicated by 0.01 increments to the version number. These occur as bugs are fixed or very simple features added to the code. These changes occur every few months during the early life of a gold version, and almost not at all, towards the end. Very minor changes are indicated by a letter after the numbers. The last version of C90 was 90.05
Revision History: A complete set of changes to the current gold version is maintained in the changes page associated with each version.
Hot Fixes: These are small changes to the current version of the code which will be incorporated in the next incremental change. Instructions for the fixes are maintained in the Hot Fixes page associated with each version.
The mailing list: Email announcing minor changes will be sent to everyone on the mailing list.

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Last changed 04/05/03.
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