PURNA CHANDRA BISWAL, Ph.D. (Indian Institute of Science, Bangalore), is Assistant Professor of Mathematics at Parala Maharaja Engineering College, Berhampur, Odisha. Earlier, Dr. Biswal served at the National Institute of Science and Technology, Berhampur and worked for three years in the department of mathematics at the Birla Institute of Technology and Science, Pilani. He has authored eight books, out of which six are published by PHI Learning, Delhi.