The Man Who Knew Infinity is a 2015 British biographical drama film about the Indian mathematician Srinivasa Ramanujan, based on the 1991 book of the same name by Robert Kanigel.

The film stars Dev Patel as Srinivasa Ramanujan, a real-life mathematician who, after growing up poor in Madras, India, earns admittance to Cambridge University during World War I, where he becomes a pioneer in mathematical theories with the guidance of his professor, G. H. Hardy, portrayed by Jeremy Irons.

[8] At the turn of the twentieth century, Srinivasa Ramanujan is a struggling and indigent citizen in the city of Madras in India working at menial jobs at the edge of poverty.

Ramanujan is eventually reunited with his family in India, though his declining health, exacerbated by poor housing and harsh winter weather in England, ultimately takes its toll and leads to his death aged 32, soon after his recognition as a mathematician of international merit and importance.

The critics' consensus reads: "The Man Who Knew Infinity might be a tad too conventional to truly do its subject justice, but Dev Patel (Srinivasa Ramanujan) and Jeremy Irons (G.H.

The old-fashioned virtues of a well-told tale and a particularly fine performance from Jeremy Irons should endear the film to that supposedly under-served older demographic who like to turn out for a weekday matinee ...

Mathematics plays a key role in the story, but in a way that is entirely accessible, allowing the viewer to comprehend the advances that Ramanujan made and why his legacy remains so important almost a century after his death.

George E. Andrews, former President of the American Mathematical Society, praised the film for its moving portrayal of the deep relationship between Ramanujan and Hardy.