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Дата изменения: Thu Jun 29 00:05:15 2006 Дата индексирования: Sat Dec 22 10:50:39 2007 Кодировка: Поисковые слова: annular solar eclipse |
The weighting factor in equations 1 and 3 prevents ugly distortions of the smoothed output
near the ends of the range of
at
and
. This treatment is also desirable near holes in the mask. To prevent this `droop' in the output close to holes, equation 2 is modified to the following:
(The specifications for and
should be amended in analogous fashion.) It should be pointed out that this cosmetic improvement is achieved at the cost of a little less noise suppression in these channels.
Similar costs are incurred by another appearence-enhancing feature of colsmooth, namely the ability to `paper over' holes in the mask which are significantly smaller than the width of the convolver. The size of holes to be interpolated is provided via the integer parameter fillholewidth. The interpolation is implemented by employing two different masks: let's us call them
and
. The one (
) that appears in equation 3.3.1 and the analogous equations for
and
is left unchanged. The other (
), which appears in equation 4 and the analogous equation for uncertainties
, is for the most part set equal to
; the exception being within stretches of contiguous
channels of length=fillholewidth:
within such stretches is set to `true'. The result is that
(and
) within these stretches or gaps is calculated as a weighted sum of only those values of
that fall outside the gap. The results are acceptable provided the sum of those parts of the convolver that fall outside the gap onto the valid parts of
is not too small a fraction of the total sum of the convolver.
Note that the default setting of fillholewidth=0 disables any hole-filling.
XMM-Newton SOC/SSC -- 2006-06-28