Let I\subset K[x,y] be a -primary monomial ideal where K is a field.
This paper produces an algorithm for computing the Ratliff-Rush closure I for
the ideal I= whenever m_{i} is contained in the integral closure
of the ideal . This generalizes of the work of Crispin
\cite{Cri}. Also, it provides generalizations and answers for some questions
given in \cite{HJLS}, and enables us to construct infinite families of
Ratliff-Rush ideals