f_delt is used as a check to see if the channel spacing matches the ongoing average. A check on f_res is also done. These warning messages can be supressed by setting the /quiet flag. The warning message is issued if the two values do not agree to within f_delt/nchan.

If a weight (wt) is not supplied, it will be teff*f_res/Tsys^2

wt can either be a scalar or it can be a vector having the same number of elements as data.

If all of data is blanked (not a number) then it is complete ignored and the accumulated weight, times, and system temperatures are unchanged. If individual regions are blanked - the weight at those channels is 0. When an average is requested (accumave) this weight array is used to rescale the data. That weight array is also available when the average is requested. If that weight array is used as input in a future average, the averaging can continue from the same point as before.

If all of the weight values (supplied or the default value as described above) are not finite (not a number) this routine behaves as if the data are blanked and the data are ignored and the accumulated values are unchanged.

If the Tsys value is not finite (not a number) but the weights and data are at least partially finite, then the Tsys value is ignored in the ongoing weighted Tsys^2 accumulation. The weights used in the Tsys^2 accumulation are kept separate from the data weights.

Version

$Id$

Parameters
accumbuf in, required accum_struct structure	The structure to hold the results of this accumlation. Care must be taken if this is !g.accumbuf. Simply passing it in will not work because global values are passed by value not reference. See the code in accum.pro for an example of how to use this in that case.
data in, required float array	The data to add to the accumulation structure. It must have the same number of elements as the ongoing accumulation (if this is not the first one added in).
teff in, optional float	Effective integration time (s).
tsys in, required float	System temperature (K).
f_res in, required float	Frequency resolution (Hz). This is usually not the same as the channel spacing. It is always positive.
tint in, required float	Integration time (s). Time spent taking data, including blanking time (duration). If not supplied, teff will be used.
f_delt in, required float	Channel spacing.

Keywords
wt in, optional float	Weight to give this data.
quiet in, optional boolean	If set, suppress warning messages about f_res and f_delt not matching values in accumbuf.