### USER time

The USER time is the time spent in CLASS and Gildas code in general. CLASS developpers can act on this time by improving the algorithms.

Figure: SYSTEM and USER times for the three CLASS output files type: NEW (old type), SINGLE and MULTIPLE (new type). Numbers indicate the number of channels per spectrum. Dashed lines are power law functions ( ) with their exponent.

Fig. displays the USER time as a function of the number of spectra written, for several number of channels per spectrum and for all the possible file types. We can observe that:

- with the NEW (old) file type, for more than spectra per file, the USER time was diverging. We can notice that the limit functions were not depending on the number of channels (lines converge), and we can observe the dependency predicted at section .
- the USER time was considerably improved thanks to the new file types. For high number of spectra, it is a power law which power was decreased from 2 to 1, as expected in section .

Figure: USER time for two CLASS output files type, but with time vs number of channels per spectrum. Left: keyword NEW (old type), right: SINGLE (new type). Numbers indicate the number of spectra written, and the dashed lines a linear increase of the time with the number of channels per spectrum.

Fig. shows the same USER time values, but the number of channels per spectrum is now used as X-axis, for different number of spectra written. We can confirm that:

- the USER time is proportional to the number of channels, when this number is large enough,
- with the SINGLE and MULTIPLE file types, USER time is much lower than with the NEW file type.