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Epoch Folding Functions
The epoch folding function implements the L-statistic, as described by
Davies (1990, MNRAS, vol. 244, pp. 93-95).
- sitar_epfold_rate( t, rate [, pstart, pstop] [; nphs=#, nsrch=#, loggrid, prds=array] )
Epoch fold a rate lightcurve for a range of trial periods, and return the statistical
value of the period.
Run as: isis> fold = sitar_epfold_rate(t,rate,pstart,pstop;nphs=#,nsrch=#,prds=array);
Variables in [] are optional (qualifiers after the semi-colon).
Omitted variables take on default values.
Inputs:
-
t : Times at which rates are measured
-
rate : Lightcurve rate
-
pstart : Starting value of periods to search
-
pstop : Stopping value of periods to search
(Semi-)Optional Inputs (required if qualifier prds=array not set):
-
pstart : Starting value of periods to search
-
pstop : Stopping value of periods to search
Optional Qualifier Inputs:
-
nphs : Number of phase bins in folded lightcurve
Default = 20, minimum = 2 (unless prds is set)
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nsrch : abs(nsrch) = number of periods to search.
-
loggrid : If input, the period search grid is logarithmic.
-
prds : Alternative array of periods to search
Outputs:
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fold.prds : Array of trial periods
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fold.lstat : Array of L-statistic for trial period
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fold.lsig : Array of log10 of *single trial* significance levels.
Note: This requires use of the GNU Scientific Library package from the S-Lang Modules Packages.
Otherwise, the array defaults to a value of 1.
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fold.nphs : Array of number of phases (<= nphs) at a given period that had data.
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