By that point the mathematics department risked losing Suri to writing altogether. With a novel translated into 22 languages and shortlisted for the respected PEN/Faulkner Award, many novelists would happily abandon academe to write full time. But Suri's numerical interests continued to consume him. 'It would be just too difficult to sit at home and write all day,' he says. 'You have to wait many years for any gratification.'

Elegantly dressed in a gold-striped shirt and tan Versace suit, Suri exhibits angular features and careful, professorial speech. He exudes the neatness and precision of someone drawn to mathematical formulae and finely chiselled prose.

Over his black cod with miso at a Japanese restaurant in New York, where he has commuted from his Washington home, Suri explains that he started writing after becoming an academic and deciding he needed an interest. His first short story, The Tyranny of Vegetables, was printed in Cyrillic after an editor asked him for a story without telling him it was for a Bulgarian journal.

It was only after he began writing about India that he found an assured voice. 'When I first started I was writing things that were not geographically specific. Then I wrote a story about India and the writing seemed much more alive.'

Suri showed the first two chapters of The Death of Vishnu to his writing instructor, novelist Vikram Chandra, who pressed him to complete the novel. 'He said, 'This is going to be a real trenchant novel.' That word trenchant gave me a year of writer's block because all I had to do was write this 'trenchant novel' and I couldn't do it.' But Suri became unblocked after a five-day workshop with American writer Michael Cunningham, who told him: 'You are a writer. You have to do this at any cost.'

He still had much to learn. When influential literary agent Nicole Aragi agreed to represent him, Suri travelled to New York to interrogate her. 'I had no idea how difficult it was to find an agent so I really tried to trip her up. After I put her through all this, she told me that she gets about 20 applications a week and takes only two or three a year.'

The Death of Vishnu explores various lives in a Mumbai apartment block modelled on the building in which Suri grew up, where an alcoholic odd-jobs man named Vishnu lived on the landing. 'I saw his death and I wanted to give some meaning to it. It was a question of coming up with a background and life,' he says.

Though Suri, an only child, lived with his parents in a single room of a flat shared with other families, they scrimped to send him to an elite school. 'I was careful never to invite people over because I was always anxious about people finding out about my humble origins,' he says.

He discovered privacy for the first time on moving to the US to pursue his PhD in 1979, which enabled him to come out as gay and find a partner. 'I didn't meet a single gay person in India. It was completely invisible.' In India then, 'whether you were gay or straight it was a very closed society where there wasn't any premarital sex and there wasn't much dating. Everybody was in the same boat.'

Suri's move was traumatic for his parents, planting in him an enduring sense of responsibility for their happiness. After years of receiving letters every second day from her son, his mother Prem wrote to Guinness World Records but was told there was no entry for which she could qualify. Suri returns to India three times a year to visit Prem, now in her 80s, whose family were Hindu refugees from Pakistan after Partition in 1947.

The tensions between Hindus and Muslims in post-independence India form a backdrop to Suri's newest novel, The Age of Shiva. Whereas The Death of Vishnu takes place in one day in a single building, The Age of Shiva incorporates several decades and cities, telling a story surely shaped by Suri's intense bond with his mother.

The novel's narrator, Meera, marries the handsome but remote Dev, an aspiring pop singer from a less affluent family. Even before Dev descends into depression and alcoholism, Meera realises her mistake. She sees the birth of her son, Ashvin, as offering an escape from her bleak life; she becomes devoted to him with a suffocating and latently sexual ardour.

The novel is partly narrated by Meera in the second person addressing her son, which Suri says makes the reader 'really get to see how close this woman's bond is with her son'. Suri speculates that his homosexuality contributed to his depiction of the mother-son relationship because 'being gay means that the strongest relation you have with a woman is probably with your mother'.

Writing in the voice of an assertive female was second nature given his family's history of independent women.

Suri's grandfather died soon after his mother fled with her parents and three siblings from Pakistan, leaving five women to fend for themselves in a rigidly patriarchal society. Desperate for a job, Prem wrote to Indira Gandhi - and served as her secretary in 1952 before becoming a teacher. Suri's father Ram was an assistant music director in Bollywood and Suri's familiarity with that milieu fed into his portrayal of Dev's dispiriting experiences in the music industry.

Meera's story reflects the Oedipal myth of Shiva's wife, Parvati, who, neglected by her puritanical husband, trained all her attention on her son at Shiva's expense. Suri set out to remedy the cliche of Shiva as a purely destructive force that 'goes around with a flaming sword and smites down everything'. He is a destroyer 'but in a very different sense', he says. 'He's an ascetic and he withdraws from the world and his presence is needed for the world to keep going. It's without him that the world starts dying.'

The Age of Shiva forms the second part of a triptych about the trinity of Hindu deities, Brahma, Vishnu and Shiva. But Suri says the trilogy has become primarily about India rather than mythology, with The Death of Vishnu being a snapshot of contemporary India and The Age of Shiva tracing its history. His next novel, about Brahma, will imagine India in the near future. After writing 100 pages set in the US, he recently started again from scratch after deciding to set the work entirely in India.

'I keep being pulled back there,' Suri muses. 'I don't know if some day I'll break free.'

Writer's notes

Genre: literary fiction

Latest book: The Age of Shiva

Current project: another novel

Age: 48

Lives: Washington

Family: Larry Cole, engineer, partner for 18 years

Other works: The Death of Vishnu

Other jobs: Mathematics professor

What the papers say: '[The] constant juxtaposing of the banal and the profound, the domestic and the quasi-supernatural, the earthy and the lyric, combined with Suri's feeling for his characters ... makes The Death of Vishnu not just a very fine Indian novel, but a superb, cinematic performance of texture and humour.' - The Irish Times

Author's bookshelf

The Elephanta Suite by Paul Theroux

'Three novellas set in India. The middle novella summarises the dynamics of the new relation between east and west.'

No God in Sight by Altaf Tyrewala

'He has a circular structure where he jumps from one story to another and comes back to

the end. Set in Bombay, it is wonderful.'

India After Gandhi: The History of the World's Largest Democracy by Ramachandra Guha

'A voluminous book on the history of India after independence. It brings things to life which I always thought would be very boring to read about.'

Shame by Salman Rushdie

'One of the first literary novels that I read, way back in the 1980s. I used to read a lot of genre fiction and someone presented me with this and it was completely unlike anything I'd ever read before.'

Maximum City: Bombay Lost and Found by Suketu Mehta

'He really gets beneath the skin of Bombay. Even though I lived there for 20 years he showed

me sides of the city that I didn't know existed.'