Thursday 10 October 2013

Before He was Fibonacci

The following is a combination of two blogs printed at different times about the use of the name Fibonacci for Leonardo of Pisa, author of the famous Liber Abaci which was a major force in introducing Arabic numerals to the West.  I hope you enjoy.

A reader named Vlorbik picked up on my "factoid interlude" in my last blog that no one called Fibonacci by that name in his lifetime. When he asked, "Who did?", I realized that thousands of students (and their teachers) probably do not know that name was added well after his death. So here is the story, as well as I know it, from the notes on my Math Words Etymology page.
According to Paul J. Nahin, author of AN IMAGINARY TALE, the name Fibonacci was not common until centuries after Leonardo's death, and during his lifetime he was called Bigollo, a slang term for a loafer, and my wife's favorite term for me, drawn from the word bighellone. Julio Gonzalez Cabillon has written, "The name 'Fibonacci' most probably originated with the historian of mathematics Guillaume Libri (1803-1869)."

In September of 2001, Heinz Lueneburg posted a note that seemed to suggest that there may have been earlier uses than Julio suggested. He writes (with some editing by me):

I was in Rome and checked the Boncompagni paper
I quoted in my posting of August 28. The paper starts with the diskussion of what is known of persons of the Bonacci family other than Leonardo: One Matteo Bonacci is known because he is mentioned as a witness of the treaty Pisa and Genova signed on February 13, 1188.
Then he lists the names of authors who use the name "Leonardo Pisano".
Then he lists the names of authors who use the name "Fibonacci".
John Leslie 1820
Cossali 1797-99
Giovanni Gabriello Grimaldi 1790-1792
Libri 1838-1841
Chasles 1837
Nicollet 1811-1818
S. Ersch & I. G. Gruber 1818 and subsequent years
August de Morgan 1847. He also uses Bonacci.

Then he lists the names of authors who explain "Fibinacci = filio Bonacci"
Flaminio dal Borgo 1765
Tiraboschi 1822-1828
Ranieri Tempesti 1787
Giovanni Andres 1808-1817
Grimaldi 1790-1792
Libri 1838-1841

Then his arguments for Fibonacci = de filiis Bonacci follow.
Then he discusses the sobriquet Bigollone, Bigollo, Bigoloso.
Finally, in the major part of the paper, he discusses the various manuscripts of the various works of Fibonacci still in existence.
The question "who gets the credit?" is still open.
Regards, Heinz Lueneburg

My personal pick is Flaminio dal Borgo 1765

By the way, a personal footnote, On the last day of my first visit to Pisa I missed a turn and came upon the Via Fibonacci quite by accident.

And just a followup, we DO know who first invented the term "Fibonacci Sequence". It was created by Edouard Anatole Lucas, who is also known for inventing the "Towers of Hanoi" puzzle.

I pretty much thought I had covered the list, as uncertain as it was, and it must have been no sooner than 1765.  Finally I found another reputable confirmation in Keith Devlin's The Man of Numbers, but also, ... HOW HAD I MISSED THIS STATEMENT! 

In one early section he writes, "He refers to himself as filius Bonacci, a Latin phrase  that translates literally as 'son of Bonacci'.  But Bonacci was not his father's name, so we should perhaps translate the phrase as 'of the Bonacci family'."  
He then goes on to credit the origin of the present day nickname "Fibonacci" to the historian Guillaume Libri in 1838.  A common attribution I had included before the long list of earlier uses provided by Heinz Lueneburg in the post linked above.  Heinz goes on to opt for, "My personal pick is Flaminio dal Borgo 1765." 

Ok, so very recently searching through the Devlin book again for a mention of an old problem that Fibonacci had included somewhere, I came across this line (page 128, 2nd paragraph:

The oldest abacus (calculations) books still in existence date from around 1290.  On of them is livero del abbecho.  Its unknown author describes it as ... (long Italian phrase ending in).. del'figluogle Bonacie da Pisa" (abacus book according to the opinion of master Leonardo Fibonacci), perhaps making it one of the earliest to make such use of Leonardo's name.  

Now 1290 is way before Libri, or even Flaminio dal Borgo.... like 500 years before.  So, I get the feeling we may still be waiting for another historian who will find that , for whatever family relation he sought to mean by it, we may someday come to find out that during his life, at least after he became famous throughout Europe, they did speak of this master of abacus as The Pisan, Fibonacci.  

By the way, Devlin's book has a wonderful photograph of the surviving statue of Fibonacci standing amid the rubble of the bombed out central bridge in Pisa during WWII, before it was moved to the Camposanto. 

No comments: