Leanardo of Pisa (Fibonacci)

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Leanardo of Pisa (Fibonacci)
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Leonardo da Pisa 2000x3008.jpg
Leanardo of Pisa was the son of Guglielmo, a mercantile trade statesman. Traveling with his father, Leanardo was exposed to the Arabic number system of nine digits, and published a book in 1202 named Libra Abaci (Book of Caculuation). Romanesque Europe was yet using Roman numerals for cyphers, and Leonardo was first to introduce the Arabic number system —and algebra.

Leanardo's father, Guglielmo, was nicknamed Bonaccio (good natured man). This good nature of Leanardo's father was likely a factor that aided his trading business, and perhaps was a lasting memory of the cultural influence his trading route established, as it was about a century after Leanardo's death that he was called Filius Bonacci, or son of Bonaccio. This was shortened in common vernacular to Fibonacci, which is the name ascribed to Leanardo of Pisa to this day.

Leanardo was not the inventor of the Fibonacci number sequence, but discovered this from the Arab scholars that taught him Arabic numbers and the technique of reckoning the algor, (the thing), the Arabic technique of algebra. The origin of the Fibonacci number sequence lies in ancient Vedic mathematics of India (per Jain, et al).

The young Fibonacci

Excerpt from: Eight Hundred Years Young by A. F. Horadam, Department of Mathematics, University of New England Full source by permission: http://faculty.evansville.edu/ck6/bstud/fibo.html

Fibonacci's father is mentioned by name by a contemporary writer as Gulielmus (William). Not much is known about the father except that he was a state official associated with the new mercantile class which had emerged from the commercial revolution.

No portraits of Fibonacci exist. Possibly, the imaginative description of the education, clothes and housing of people of medieval Pisa, as given in4, was applicable to Fibonacci.

All that we do know about Fibonacci is contained in a few sentences about himself in the 1228 edition of his famous Liber Abbaci (sometimes spelt Liber Abaci). The translation of these passages, along with the original Latin, is given by Grimm5 as follows:

After my father's appointment by his homeland as state official in the customs house of Bugia for the Pisan merchants who thronged to it, he took charge; and in view of its future usefulness and convenience, had me in my boyhood come to him and there wanted me to devote myself to and be instructed in the study of calculation for some days. There, following my introduction, as a consequence of marvelous instruction in the art, to the nine digits of the Hindus, the knowledge of the art very much appealed to me before all others, and for it I realized that all its aspects were studied in Egypt, Syria, Greece, Sicily, and Provence, with their varying methods; and at these places thereafter, while on business. I pursued my study in depth and learned the give-and-take of disputation. But all this even, and the algorism, as well as the art of Pythagoras I considered as almost a mistake in respect to the method of the Hindus. Therefore, embracing more stringently that method of the Hindus, and taking stricter pains in its study, while adding certain things from my own understanding and inserting also certain things from the niceties of Euclid's geometric art. I have striven to compose this book in its entirety as understandably as I could, dividing it into fifteen chapters. Almost everything which I have introduced I have displayed with exact proof, in order that those further seeking this knowledge, with its pre-eminent method, might be instructed, and further, in order that the Latin people might not be discovered to be without it, as they have been up to now. If I have perchance omitted anything more or less proper or necessary, I beg indulgence, since there is no one who is blameless and utterly provident in all things.

From this tantalizingly brief glimpse of Fibonacci's life, we gain some insight into his personality and the mathematical quality of his mind. Quite apart from the intellectual curiosity and excitement which these passages reveal, they leave us with a respect and warmth of feeling for the modest humility of the man. "Leonardo's humility graces his genius", says Grimm[5].

† The port of Bugia (modern Bougie in Algeria) was a thriving source of raw materials for furs and leather, two of Pisa's industries.
[4] Gies, Joseph and Gies, Frances, Leonard of Pisa and the New Mathematics of the Middle Ages, Thomas Y. Crowell, 1969.
[5] Grimm, R. E., "The Autobiography of Leonardo Pisano", Fibonacci Quarterly, Vol. 11, No. 1, February 1973, pp. 99-104.

See also

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