plssub: Set the number of subpages in x and y 

DESCRIPTION:

    This function is examples 1,2,14,21,25,27. 

SYNOPSIS:

plssub(nx, ny)

ARGUMENTS:

    nx (PLINT, input) :    Number of windows in x direction (i.e., number
    of window columns). 

    ny (PLINT, input) :    Number of windows in y direction (i.e., number
    of window rows).