Starring Dev Patel. Rated PG.

The poetic side of mathematics is extremely difficult to dramatize. That’s why A Beautiful Mind didn’t even try. The Man Who Knew Infinity gives it a good college effort, actually breaking down some equations and explaining why they might matter to people who understand them better than the rest of us. The movie frequently fails in the drama department, however, although some of the performances reach for higher planes.

Here, Slumdog Millionaire’s Dev Patel leaves his Marigold Hotel to play Srinivasa Ramanujan, a real-life math wiz who grew up in Madras, India. He came from a Brahmin family, which writer-director Matthew Brown, making his feature debut, forgets to tell us. The movie also ignores several serious illnesses that would contribute to his early death, and the fact that he married a 10-year-old girl (who actually made it to 1994), instead concentrating on his long-distance marriage to a patient 20-something played by U.S.–born Devika Bhise.

In any case, Ramanujan’s parents had fallen on hard times by the time he sailed to England in 1914, to work with Cambridge math lecturer G.H. Hardy. Jeremy Irons utterly steals the movie as this learned don with poor people skills. Carrying the intellectual weight and moral queasiness of the British Empire on his slumped shoulders, Hardy comes to see that what he calls “intuition” represents a taller order of mathematical imagination. Meanwhile, the younger man reluctantly adopts the “rigour” of the proof-demanding institution.

Unfortunately, the intrusion of the First World War—or “Trouble on the continent?”, as someone helpfully puts it—is handled clumsily, as are many other contextual elements. The flashback visits to India feel perfunctory. The Cambridge scenes feel much more urgent, with interesting side characters, like philosophical superstar Bertrand Russell, well played by Jeremy Northam, and other top Brits huddling in dark, book-lined warrens. Their dialogue sometimes feels forced, but the movie comes alive whenever the screen yields to Irons and his pained dissections of life’s elusive formulations.