Lasting knowledge comes from understanding and we have tried our best to
make this book more understandable. Although mass of the book is
limited, but new editions always have a tendency to grow up. Anyways,
more illustrations have been added in this book. All the topics have
been extensively re-viewed and then written. Some additions and a few
subtractions have been made and all the knowledge is updated. So what
you hold in your hands is a concentrated extract of knowledge from
several text books. The hard work needed to improve a book and then
getting it published was really too much but we sincerely hope that our
efforts will make life easier for the students. We wish you all good
luck. Tank you for your immense feed back and appreciation and we hope
you will continue to help us with your remarks and suggestions.