pp_correlate

       correlates a pulse profile with a template profile
       and returns the index of the shifted profile that matches
       the template at best

       lightcurve

 index=pp_correlate(template, testarray, minsubtract=1, chatty=1)

       template : array of a template pulse profile (light curve)
       testarray: array of a light curve, which should be shifted
                  to match the template at best

       none

       minsubtract : By default, the mean value of both arrays subtracted
                     before correlation. Setting minsubtract will
                     subtract the minimum from both array instead of the
                     mean value.
       chatty      : if set, some output is printed during processing

       Result      : The index of testarray, which matches best template[0].
                     If template and testarray are not of same size, a value
                     of -1 is returned.

       none

       * testarray must have the same size as template

       1. The mean value or the minimum value is subtracted from
          both arrays (depending on keyword minsubtract)
       2. Both arrays are scaled with the mean value of their absolute
          values so that they are comparable
       3. testarray is shifted to all possible positions and for each
          position chi-squared is computed
       4. The index of the minimum chi-squared is returned

       nbins=N_ELEMENTS(template)
       i=pp_correlate(template, testarray, minsubtract=1, chatty=1)
       ; or use default:
       i=pp_correlate(template, testarray)
       ; now shift testarray to index i:
       IF (i GT 0) THEN BEGIN
               index=[INDGEN(nbins-i)+i,INDGEN(i)]
               testarray=testarray[index]
       ENDIF

 $Log: pp_correlate.pro,v $
 Revision 1.1  2006/03/23 09:53:52  barnsted
 initial release

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