:plot x y function

:plot x y
    setlocal
        set "c=%~3"
        set /a "_y=%~2", "_x=%~1", "_x2=%~1 + 1"
        (endlocal
            set "_[%_y%]=!_[%_y%]:~0,%_x%!%c:~0,1%!_[%_y%]:~%_x2%!"
        )
goto :eof