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help for ^circcent^
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Centring circular data
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    ^circcent^ varname ^,  g^enerate^(^newvar^)^ [ ^c^entre^(^string^)^ ^p^os ]

Description
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^circcent^ takes varname, a circular variable between 0 and 360 degrees,
and produces a new variable newvar centring varname on the direction(s)
given by ^centre(^ ^)^. By default, newvar varies from -180 degrees to
180 degrees, with centre at 0 degrees. If the ^pos^ option is used,
newvar varies from 0 to 360 degrees, with centre at 180 degrees.


Options
-------

^generate(^newvar^)^ specifies the name of the new variable and is not
    optional.

^centre(^string^)^ specifies the direction(s) which correspond to the
    centre(s) of newvar. The mean direction of varname is one
    possibility. Note that this is produced by ^circsumm^ and deposited
    in global macro S_2. Other possibilities are other constants or the
    name of a variable containing one or more directions.

^pos^ forces newvar to be non-negative, varying from 0 to 360 degrees.
    180 degrees corresponds to the direction(s) specified by ^centre(^ ^)^.


Examples
--------

        . ^circsumm wallasp^
        . ^circcent wallasp, gen(newwall) centre($S_2)^

        . ^circcent wallasp, gen(newwall) centre(45)^
        . ^circcent wallasp, gen(newwall) centre(45) pos^

        . ^circcent ori, gen(relflow) centre(iceflow)


Author
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         Nicholas J. Cox, University of Durham, U.K.
         n.j.cox@@durham.ac.uk


Also see
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On-line:  help for @circsumm@
