plsmaj: Set length of major ticks 

DESCRIPTION:

    This sets up the length of the major ticks.  The actual length is the
    product of the default length and a scaling factor as for character
    height. 

SYNOPSIS:

plsmaj(def, scale)

ARGUMENTS:

    def (PLFLT, input) :    The default length of a major tick in
    millimeters, should be set to zero if the default length is to
    remain unchanged. 

    scale (PLFLT, input) :    Scale factor to be applied to default to get
    actual tick length.