MAP_POLAR /COMPUTE

        [ADVANCED\]MAP_POLAR GenericBegin [GenericEnd] [/COMPUTE [Threshold]]

    Compute the Polarization Fraction image 'GenericBegin'"-P"'.Type',  and  the
    Polarization  Angle  image 'GenericBegin'"-A"'GenericEnd" from the 'Generic-
    Name'"-K"'GenericEnd' images where -K is all of the -I, -Q,  and  -U  Stokes
    images.

    The derivation is only made on pixels that are brighter than Threshold sigma
    in  the  Stokes I image. The use of the /COMPUTE option reset all parameters
    that control further display to their default values.