[vsnet-chat 294] Re: PDM and other methods

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

Victor R. Ruiz wrote in [vsnet-chat 274]:

>   I know there are some sources and programs in the VSNET ftp but I
> haven't found a line on how to use them. Are there any documents or help
> files?

    Some programs contributed from VSNET members do contain documents,
but unfortunately many of the collection have no documents other than
'a line' for prompting parameters (if you have a chance, try 'pdm.exe'
without options).

    Regarding PDM for DOS (pdm.exe), my program, first make a file containing
a time series observations, say,

50217.9590   0.0616
50217.9601   0.0825
50217.9613   0.0064
50217.9625   0.0932
50217.9637   0.0141
50217.9655  -0.0471
50217.9667  -0.0612
50217.9678  -0.1364
50217.9690   0.0105
50217.9702  -0.0816
50217.9749  -0.1721
50217.9761  -0.1903
(file truncated)

    The first column represents the time in JD (HJD), the second column
magnitude (differential value in this example).  Save the file as
test.dat for example.  The data file should not contain blank lines.

    Then try from the DOS prompt

pdm test.dat 0.02 0.1 1000 >test.pdm
              (1) (2)  (3)

  (1) the minimum period of the search
  (2) the maximum period of the search
  (3) fineness (typically 1000)

    The yielded file "test.pdm" will then contain the theta values
corresponding to the period tried.  Each output line contains a trial period
and theta.  By drawing a graph using some plotting tool, you will easily find
a familiar theta diagram shown in many literatures.

Regards,
Taichi Kato

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