"Algorithm"
Earlier the Persian author Abu Abd Allah, Mohammed ibn Mûsâ al-Khowârizmî (usually abbreviated to Al-Khwarizmi or, more accurately, Al-Khowârizmî) had written a book which included the rules of arithmetic for the decimal positional number system, called Kitab al jabr w'al-muqabala (Rules of restoration and reduction) dating from about 825 AD. D E Knuth (in the third edition of his "Fundamental Algorithms", not in earlier ones) gives the full name above and says it can be translated as Father of Abdullah, Mohammed, son of Moses, native of the town of Al-Khowârizmî. He was an astromomer to the caliph at Baghdad (now in Iraq).
Al-Khowârizmî is the region south and to the east of the Aral Sea around the town now called Khiva (or Urgench) on the Amu Darya river. It was part of the Silk Route, a major trading pathway between the East and Europe. In 1200 it was in Persia but today is in Uzbekistan, part of the former USSR, north of Iran, which gained its independence in 1991.
Prof Don Knuth has a picture of a postage stamp issued by the USSR in 1983 to commemorate al-Khowârizmî 1200 year anniversary of his probable birth date.
From the title of this book Kitab al jabr w'al-muqabala we derive our modern word algebra.
The Persian author's name is commemorated in the word algorithm. It has changed over the years from an original European pronunciation and latinisation of algorism. Algorithms were known of before Al-Khowârizmî's writings, (for example, Euclid's Elements is full of algorithms for geometry, including one to find the greatest common divisor of two numbers called Euclid's algorithm today).
The USA Library of Congress has a list of citations of Al-Khowârizmî and his works.
Our modern word "algorithm" does not just apply to the rules of arithmetic but means any precise set of instructions for performing a computation whether this be
a method followed by humans, for example:
a cooking recipe;
a knitting pattern;
travel instructions;
a car manual page for example, on how to remove the gear-box;
a medical procedure such as removing your appendix;
a calculation by human computors : two examples are:
William Shanks who computed the value of pi to 707 decimal places by hand last century over about 20 years up to 1873 - but he was wrong at the 526-th place when it was checked by desk calculators in 1944!
Earlier Johann Dase had computed pi correctly to 205 decimal places in 1844 when aged 20 but this was done completely in his head just writing the number down after working on it for two months!!
or mechanically by machines (such as placing chips and components at correct places on a circuit board to go inside your TV)
or automatically by electronic computers which store the instructions as well as data to work on.
