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Historical status

In the original CLASS file format, any observation could have different versions. When writing an observation $N$ to a CLASS file, the algorithm had to reread the $N-1$ observations and all their versions already written and check if a previous version of the same observation was already present. If yes, the version number was increased. This is typically a $N^2$ algorithm. On latest modern computer, this started becoming a limiting factor (compared to the OS/hardware incompressible time) when writing more than $10^5$ spectra per file (see section [*]).



Gildas manager 2023-06-01