x-array, y-array, <marker_symbol>;
Draw points at each x,y pair in the arrays given.

PARAMETERS
----------

x-array       -  The X-coordinate of each point.

y-array       -  The Y-coordinate of each point.

marker_symbol -  The PGPLOT marker symbol to use.
                 If omitted, then marker 2 will be used. This is
                 a plus (+) symbol.
