The 7th to the 13th century was the golden age of Muslim learning. In mathematics they contributed and invented the present arithmetical decimal system and the fundamental operations connected with it addition, subtraction, multiplication, division, exponentiation, and extracting the root. They also introduced the 'zero' concept to the world. Some of the famous mathematicians of Islam are: AL-KHOWARIZMI (780 - 850 CE) Muhammad Ibn Musa Al-Khowarizmi, the father of algebra, was a mathematician and astronomer. He was summoned to Baghdad by Al-Mamun and appointed court astronomer. From the title of his work, Hisab Al-Jabr wal Mugabalah (Book of Calculations, Restoration and Reduction), Algebra (Al-Jabr) derived its name. A Latin translation of a Muslim arithmetic text was discovered in 1857 CE at the University of Cambridge library. Entitled 'Algoritimi de Numero Indorum', the work opens with the words: 'Spoken has Algoritimi. Let us give deserved praise to God, our Leader and Defender'. It is believed that this is a copy of Al-Khowarizmi's arithmetic text which was translated into Latin in the twelfth century by an English scholar. Al-Khowarizmi left his name to the history of mathematics in the form of Algorism (the old name for arithmetic). Al-Khowarizmi emphasised that he wrote his algebra book to serve the practical needs of the people concerning matters of inheritance, legacies, partition, lawsuits and commerce. In the twelfth century Gerard of Cremona and Roberts of Chester translated the algebra of Al-Khowarizmi into Latin. Mathematicians used it all over the world until the sixteenth century. It is generally assumed that Al-Khowarizmi was born around 780 CE in the town of Kath in the oasis of Khorzen. Kath is now buried in the sand. AL-KINDI (801-873 CE) Abu Yusuf Yaqub Ibn Ishaq Al-Kindi, was born around 801 CE in Kufa during the governership of his father. The surname indicates ancestry in the royal tribe of Kindah of Yemenite origin. To his people he became known as Faylasuf Al-Arab (the philosopher of the Arabs) the first one in Islam. Among his contributions to arithmetic, Al-Kindi wrote eleven texts on numbers and numerical analysis. AL-KHARKHI Abu Bakr ibn Hussein was born in Kharkh, a suburb of Baghdad. His works covered arithmetic, algebra and geometry. His work Al-Kafi fi Al-Hisab' (Essentials of Arithmetic) covers the rules of computation. His second work, Al- Fakhri' derived its name from Al- Kharki's friend the Grand Vizier of Baghdad. Al-BATTANI (850-929 CE) Muhammad Ibn Jabir Ibn Sinan Abu Abdullah, the father of trigonometry, was born in Battan, Mesopotamia and died in Damascus in 929 CE. An Arab prince and governor of Syria, he is considered to be the greatest Muslim astronomer and mathematician. Al-Battani raised trigonometry to higher levels and computed the first table of cotangents. AL-BIRUNI (973-1050 CE) Al-Biruni was among those who laid the foundation for modern trigonometry. He was a philosopher, geographer, astronomer, physicist and mathematician. Six hundred years before Galgeo, Al-Biruni discussed the theory of the earth rotating about its own axis. Al-Biruni carried out geodisic measurements and determined the earth's circumference in a most ingenious way. With the aid of mathematics, he enabled the direction of the Qibla to be determined from anywhere in the world. In the domain of trigonometry, the theory of the functions; sine, cosine, and tangent was developed by Muslim scholars of the tenth century. Muslim scholars worked diligently in the development of plane and spherical trigonometry. The, trigonometry of Muslims is based on Ptolemy's theorem but is superior in two important respects: it employs the sine where Ptolemy used the chord and is in algebraic instead of geometric form. www.muslimheritage.com/