I have tried to explain the fundamentals to a great length so that studentsmay not feel the subject to be difficult. The treatment of the subject is unique and is in a systematic and interesting manner. Even an average student shall be able to understand the subject independently and without any difficulty. There are a large number of solved examples and some have been left for students. I shall feel highly rewarded if the students find the book useful for themselves. Any suggestion for improvement of the book from any quarter will be highly appreciated.