Sunday, October 18, 2009

Ada Lovelace

Augusta Ada King, Countess of Lovelace, born Augusta Ada Byron, was the only legitimate child of poet Lord Byron. She is widely known in modern times simply as Ada Lovelace.

She is mainly known for having written a description of Charles Babbage's early mechanical general-purpose computer, the analytical engine. She is today appreciated as the "first programmer" since she was writing programs—that is, encoding an algorithm in a form to be processed by a machine—for a machine that Babbage had not yet built. She also foresaw the capability of computers to go beyond mere calculating or number-crunching while others, including Babbage himself, focused only on these capabilities.

Ada Lovelace met and corresponded with Charles Babbage on many occasions, including socially and in relation to Babbage's Difference Engine and Analytical Engine. Babbage was impressed by Lovelace's intellect and writing skills. He called her "The Enchantress of Numbers."

During a nine-month period in 1842-43, Lovelace translated Italian mathematician Luigi Menabrea's memoir on Babbage's newest proposed machine, the Analytical Engine. With the article, she appended a set of notes. The notes are longer than the memoir itself and include, in complete detail, a method for calculating a sequence of Bernoulli numbers with the Engine, which would have run correctly had the Analytical Engine ever been built. Based on this work, Lovelace is now widely credited with being the first computer programmer and her method is recognised as the world's first computer program.

However, biographers debate the extent of her original contributions, with some holding that the programs were written by Babbage himself. Babbage wrote the following on the subject, in his Passages from the Life of a Philosopher (1846):

I then suggested that she add some notes to Menabrea's memoir, an idea which was immediately adopted. We discussed together the various illustrations that might be introduced: I suggested several but the selection was entirely her own. So also was the algebraic working out of the different problems, except, indeed, that relating to the numbers of Bernoulli, which I had offered to do to save Lady Lovelace the trouble. This she sent back to me for an amendment, having detected a grave mistake which I had made in the process.

The level of impact of Lovelace on Babbage's engines is difficult to resolve due to Babbage's tendency not to acknowledge (either orally or in writing) the influence of other people in his work. However Lovelace was certainly one of the few people who fully understood Babbage's ideas and created a program for the Analytical Engine, indeed there are all sort of clues that she might also suggested the usage of punched cards on the Babbage's second machine since her notes at Menabrea's memoir suggest she deeply understood the Jaquard's Loom as well as the Analytical Engine. Her prose also acknowledged some possibilities of the machine which Babbage never published, such as speculation that "the engine might compose elaborate and scientific pieces of music of any degree of complexity or extent".

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