Dev Patel, who essays the role of late Indian mathematician Srinivasa Ramanujan in 'The Man Who Knew Infinity', found it difficult to break down complex mathematical formulas while shooting for the film.
To make Dev understand his character better, Japanese-American mathematician Ken Ono was hired by the producers to help him around.
"I was involved because they wanted to get their mathematics right and before I knew it, I was on the sets in England, helping out with so many different things. It was, of course, difficult to explain how to be a mathematician to someone who is not a mathematician," Ono said in a statement.
"My favourite scene in the film is where Dev Patel completes a complex mathematical formula on the blackboard and one can see that he has done it in real time. My challenge was to select a formula that he could remember easily and complete it in the sequence," Ono added.
Written and directed by Matthew Brown, 'The Man Who Knew Infinity', which also stars Jeremy Irons, Devika Bhise, Stephen Fry, Toby Jones and Arundhati Nag, is slated to release on April 29 in India.
Though Ramanujan had almost no formal training in pure mathematics, he made extraordinary contributions to mathematical analysis, number theory, infinite series, and continued fractions.
He passed away at the age of 32 in 1920.