Euler,+Leonhard


 * __Leonhard Euler__**


 * Biography:**

Leonhard Euler, a Swiss mathematician known for writing many textbooks was born in Basel, Switzerland on the fourth of April, 1707. His father, Reverend Paul Euler wanted him to become a minister, and he graduated from the University of Basel in 1724 with a Master’s in philosophy, and he continued to study theology until his teacher, John Bernoulli persuaded his father to allow him to study mathematics. In 1727 Catherine I invited him to the Academy of Sciences in St. Petersburg, Russia where in 1730 he became the professor of physics, and three years later he was the professor of mathematics. At age 26 Leonhard married Katherine Gsell. Together they had 13 children, but only five of them survived infancy. He claimed that it was while he was holding a baby and children playing around his feet that he made his most important discoveries. Leonhard Euler remained in St. Petersburg until 1741 when Frederick the Great called him to Berlin where he was the director of mathematics at the Academy of Science. Euler would remain at that position for 25 years, until he returned to St. Petersburg in 1766 as the director of the academy. In 1771 his house caught fire, and other than his family the only items that he managed to save were his mathematical manuscripts. Shortly after the fire he had a cataract operation, which temporarily restored his vision that he had previously lost. However, he failed to take care of himself and his vision soon faded away. Blindness didn’t prevent Euler from writing textbooks; from his excellent memory he wrote and published most of his work during the last twelve years of his life when he was blind. Late in his life his health continued to deteriorate and at age 76 Leonhard Euler died of a stroke.


 * Contributio****ns:**

Not only did Leonhard Euler make discoveries in math, but in astronomy, mechanics, optics and acoustics as well. It was said that he could write and finalize a paper in as little as half an hour, about many topics including calculus of variations, calculation of planetary orbits, artillery and ballistics, shipbuilding and navigation, motion of the moon and differential calculus. In 1748 his first great textbook was published; Introducio in analysn infinitorum. Written in two volumes; the first was devoted to the theory of functions, especially logarithmic, trigonometric and exponential functions which together formed the infinite series. Volume two was an analytical study of curves and surfaces. Other books that he wrote included two great calculus textbooks. Institutiones Calculi was published in 1755 and Institutiones Calculi integralis was published in three volumes between 1768 and 1770. Also published in 1770 was an algebra textbook, Vollstandige Anleitung zur Algebra that proved many of the results that were previously stated by Pierre de Fermat. Leonhard Euler was the first person to use “sin” “cos” and “tan” as abbreviations for “sine” “cosine” and “tangent,” terms that are used in trigonometry. He was also the first to prove that e is an irrational number and he solved the Basel problem, something that no other mathematician of his time could comprehend. Throughout his life Leonhard Euler, professor, mathematician and writer, wrote more than 500 articles and textbooks, and made vast contributions to the math world.


 * Citations:**

American Mathematical Society. February 26, 2008 . Boston, Stephen. __Leonhard Euler__. 1999 Februay 22, 2008 . February 26, 2008 . Golba, Paul. March, 2007 February 26, 2008 . Planet Math. February 26, 2008 . Science World. February 22, 2008 . __The Mcgraw Hill Encyclopedia of World Biography__. New Yok: McGraw-Hill Book Company Inc., 1973.