X+Y review: A formula without a proof

In 2007 a documentary chronicling the selection process and training regimen for the British team at the 2006 International Mathematical Olympiad (IMO) aired on BBC to much acclaim. Unsurprisingly, some bright spark who saw that film – called Beautiful Young Minds – decided it had the potential to be a major motion picture.

Well, in theory. In practice, this nicely-shot, beautifully performed and well-told story always feels a bit too intimate, a bit too telly to be Billy Elliot with sums.

Loosely inspired by the life of mathematical prodigy Daniel Lightwing, Morgan Matthews’s movie strives to find the warm heart under the cold, clinical surface of a human calculator with Asperger syndrome.

Working from a carefully informed script, Asa Butterfield does good work at approximating the high-functioning end of the autistic spectrum. Just as his character, a whizz named Nathan, finds (and often demands) patterns and primes in unlikely places, John Graham’s screenplay plots out various interpersonal relationships.

The troubled co-dependency between Nathan and his heartbreakingly soft mum (Hawkins) takes central stage here, but there are, additionally, several intriguing sub-relationships, notably between Nathan and his pot-smoking maths coach with MS, Mr Humphries (Spall, excellent) and the blossoming hints of romance between Nathan and his Chinese counterpart, Zhang Mei (Yang).

Smaller characters are occupied and made meaningful by such watchable talents as Eddie Marsan and Martin McCann.

Unhappily, this ultimately feels like a formula without a proof: X+Y is plenty charming and life-affirming but it never quite entices the viewer into mathematics in the same way that a film such as Spellbound seduces us into the wonderful world of the Spelling B.