Lecturer, Indian Institute of Technology, 1963-1968, assistant professor, 1971-1978, professor, since 1978, head department mathematics, since 1986. Visiting assistant professor University Illinois, Urbana, 1969-1971. Visiting professor State University New Mexico, Las Cruces, 1980-1981, computing laboratory University Oxford, England, 1975-1976.
Reviewer American Mathematics Society, Association for Computing Machinery. Referee various international journals. Edition review board International Journal Computer Mathematics England, since 1986.
Contributor research articles to international science journals.