The routine returns true if the point f or the list/set of points f is on object obj; false if it is not; and FAIL if it is unable to reach a conclusion.

In case of FAIL, if the third optional argument is given, the condition that makes f on object l is assigned to this argument. It will be either of the form  or of the form  where expr, expr_i are maple expressions.

The command with(geom3d,IsOnObject) allows the use of the abbreviated form of this command.