21/12/2020

Al-Khwarizmi, the man who simplified multiplication.

Estátua de Al-Khwarizmi em Khiva, no Uzbequistão. Foto: Wikimedia Commons

If you've never had to multiply Roman numerals together, amidst the countless mathematical challenges you've faced, take a moment of your day and thank Abu Ja'far Muhammad ibn Musa al-Khwarizmi. It was thanks to Al-Khwarizmi that European intellectuals learned of the existence of Indo-Arabic numerals. Historians believe he came from Khwarezm, a region of Central Asia that is now part of Turkmenistan and Uzbekistan.

Considered the father of algebra, his work was disseminated thanks to Leonardo Fibonacci, an Italian mathematician who guided and encouraged Europeans in adopting Indo-Arabic numerals. This is documented in Fibonacci's book "Liber Abaci" ("Book of Calculation"), published in 1202 after studying with an Arab teacher. The work includes a reference to the text "Modum algebre et almuchabale," which quotes Al-Khwarizmi.

Al-Khwarizmi's work addresses a crucial aspect of any human being's life: performing calculations based on Roman numerals would be extremely laborious. Imagine having to calculate CXXIII by XI. Based on Hindu calculus, the mathematician revived the revolutionary idea of representing any number with only 10 simple symbols. The idea was to use them from 1 to 9, in addition to the symbol 0 to represent all numbers from one to infinity, as had already been developed by Hindu mathematicians around the 6th century.

Al-Khwarizmi was a great mathematician and astronomer who gave the West numbers and the decimal system. He also brought his knowledge to the court of Caliph al-Ma'un in Baghdad. An emigrant from eastern Persia, he enjoyed a life surrounded by books and became known for his bold way of thinking.

During the Translation Movement, which brought together scientific works from around the known world at the end of the 9th century, a significant body of Greek mathematical work was translated into Arabic. This movement included works by Euclid, Archimedes, Apollonius of Perga, Ptolemy, and Diophantus. Similarly, ancient Babylonian and Hindu mathematics, as well as the more recent contributions of Jewish scholars, were available to Islamic scholars. These differed mathematical traditions to which Al-Khwarizmi had access.

His work is so relevant to Western mathematics that even his name gave rise to the word "algorithm." In his book "Al-Jabr w'al-Muqabala," the word "algebra" appears for the first time. In the publication, the author points out that he had discovered that people need three types of numbers: units, roots, and squares, and shows how to solve equations using algebraic methods. For him, the solution was not in the numbers we needed to discover, but in a process we could apply.

With information from the BBC.