Actors Benedict Cumberbatch and Keira Knightley pose as they arrive for the European premiere of the film "The Imitation Game" at the BFI opening night gala at Leicester Square in London October 8, 2014. [Photo/Agencies]

A notebook about mathematics and computer science written by Nazi-code breaker Alan Turing, played by actor Benedict Cumberbatch in the Oscar-nominated film "The Imitation Game," will be sold at auction, Bonhams auction house said on Wednesday.

The 56-page manuscript is expected to fetch at least seven figures, with a portion of the proceeds going to charity, when it goes up for sale on April 13 in New York.

Turing was a British genius mathematician and a pioneer in computer science who hastened the end of World War Two by cracking Germany's wartime communications code.

In the notebook, which has never been seen in public and dates from 1942, Turing works on the foundations of computer science and mathematics.

"This manuscript dates from the time when Turing was engaged in the crucial task of breaking the Enigma Code," said Cassandra Hatton, senior specialist in fine books and manuscripts at Bonhams.

"Its mathematical content gives an extraordinary insight into the working mind of one of the greatest luminaries of the 20th Century," she added in a statement.

Turing never received credit for his work during World War Two and committed suicide in 1954 while receiving hormone treatment after being charged with homosexuality, which was then a crime. He was pardoned 60 years later.

He left the notebook to his friend Robin Gandy, who inscribed his own musings between the pages of Turing's notes. Gandy kept the notebook hidden until his death.

Cumberbatch, an Academy Award best actor nominee for his portrayal of Turing, described him as a gay icon who lived during a time of intolerance.

"His impact on our everyday lives is enormous, and the thought of being able to hold a manuscript that was written by him is thrilling," he said in a statement.

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