I have been searching for a book about a mathematician who figures out some math problem that ends up putting his soul into the body of a black dragon. I have never read this book, but the person who told me about it does not know the title or the author. Can someone help me identify it?
Could you be looking for The Dragon and the George by Gordon R. Dickson? The main character becomes trapped in the body of a black dragon after going through an astral projection machine.
That could perhaps be Tea With the Black Dragon by R A MacAvoy, although it's hard to be sure without more details.