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: http://xmm.vilspa.esa.es/sas/5.4.1/doc/implot/node7.html
Дата изменения: Fri Jan 10 22:39:39 2003 Дата индексирования: Sat Dec 22 07:43:12 2007 Кодировка: Поисковые слова: south pole |
It may be desirable to apply (in addition to the source selection described above) some definite upper limit to the number of sources to be plotted - say, to plot only the first 50 brightest sources. Such a limit may be difficult or impossible to achieve by use of the expression parameter. For this reason, an ncut parameter has been provided. However, this parameter alone cannot provide full versatility. It is not sufficient just to specify the number of sources to keep: it is also necessary to determine which sources to keep. This means that the sources must be sorted into a series before the series can be truncated after the ncutth member. Parameters ncutsortstyle and ncutsortexpression have been provided to allow the sources to be sorted.
Parameter ncutsortstyle has the following allowed values:
NOTE however that the infrastructure to allow the evaluation of arithmetic expressions involving column values is not yet in place (although it is expected to be very soon). At present the only acceptable format for ncutsortexpression (and for parameters radiusexpression and labelsexpression, see subsections 3.5 and 3.6) is a single column name.
XMM-Newton SOC/SSC -- 2003-01-10