<human>:  What is the name of the character who is a mathematician in the book ‘The Man Who Knew Infinity’?
<bot>: The character in the book The Man Who Knew Infinity is Ramanujan. Ramanujan was a brilliant mathematician who made many important contributions to mathematics. He lived in India and was only around for about 10 years, but he made a huge impact on the field. He was also very eccentric and was often described as "mad".