% @(#)scargltsa.hlq	10.3 (ESO-IPG) 7/9/96 09:47:21
%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 
%.COPYRIGHT (c) 1992 European Southern Observatory & Copernicus Astron. Center%.IDENT     scargltsa.hlq
%.AUTHOR    Alex Schwarzenberg-Czerny, ESO & Copernicus Astronomical Center 
%.KEYWORD   MIDAS, help files, SCARGLE/TSA
%.LANGUAGE  LATEX
%.PURPOSE   Compute discrete power spectrum 
%.VERSION   0.0               June 1992
%.RETURNS   None  
%.ENVIRON   TSA context
%-----------------------------------------------------------------------------
\se
SECTION./TSA
\es\co
SCARGLE/TSA                            15-SEPT-1992 A.Schwarzenberg-Czerny
\oc\su
SCARGLE/TSA intab outima start step nsteps
	Compute Scargle periodogramme for unevenly spaced observations
\us\pu
Purpose:  
           Compute Scargle periodogramme for unevenly spaced observations
           by a slow method. This command is recommended for the statistical
           evaluation of the significance of smooth (sinusoidal) oscillations.
           Scargle statistics for uncorrelated observations obeys an
           exponential probability distribution, with expected value of 1.
           For observations correlated in groups of size 'ncorr', divide
           value of Scargle statistics by 'ncorr'. For reference see 
           Ap.J. 263, 835.
\up\sy
Syntax:
           SCARGLE/TSA intab outima start step nsteps
\ys\pa
           intab  = name of input table, it must contain columns :TIME and 
	            :VALUE in DOUBLE PRECISION. For numerical reasons it is 
                    advisable to subtract mean from :VALUE.
\ap\pa
           outima = name of output image; its first row contains Scargle 
                    periodogram and second row contains quality factors.  Where 
                    factors are small, Scargle periodogram differs from power 
                    spectrum considerably. For unit factors Scargle periodogram 
                    differs from power spectrum only by its normalization.  
\ap\pa 
           start =  start frequency of the periodogramme, in inverse
                    units of :TIME 
\ap\pa 
           step  =  frequency step of the periodogramme, in inverse
                    units of :TIME 
\ap\pa 
           nsteps = number of frequencies of the periodogramme, in inverse
                    units of :TIME 
\ap\sa
See also:
           SHOW/TSA, SET/TSA, AOV/TSA, POWER/TSA
\as\no
Note: 
           By default 'intab', 'outima', 'start', 'step' and 'nsteps' 
           retain their values from the last use of TSA commands, unless 
           explicitly specified.
\\
           For the detection of signals with  sharp features use AOV/TSA 
           instead. 
\on\exs
Examples:
\ex
           SCARGLE/TSA LCURVE PERIODG 0.01 0.01 100 
\xe\ex
           SCARGLE/TSA ? ? 0.2 0.0001
           You may run this command after the first example to study the 
           frequency range from 0.2 till 0.21 in more detail.
\xe\sxe
