This book is written in accordance with the syllabus for the Degree Semester of different Universities in the country and is intended to be used as a text book and reference book by the students of Under Graduate, Post Graduate and Engineering students as well. 
 
In this book, each chapter has been written elaborately with due care without going into unnecessary details but is written in very simple language easily understandable to the students. Great care has been taken in writing the proofs of the theorems to make them as simple, clear and lucid as possible. Numerous worked out examples will help the students to understand the theory and concepts so that they can get clear idea and can easily solve other problems. 
 
Finally, I take this opportunity to express sincere thanks to the publisher of this book, for the special care taken to bring out this edition of the book. Last but not the least, I must not fail to mention my sincerest appreciation and thanks to my beloved wife, my family, my distinguished colleagues and friends and especially my students, without whose inspiration, I would not be able to bring out this book in its present form. I would acknowledge any suggestions for improvements of the book in future edition.