Leonhard Euler

Leonhard Euler married Katharina Gsell, the daughter of a painter in 1734. The couple had 13 children though only five survived their infancy.

He suffered a near-fatal fever in 1735 which caused severe deterioration in his eyesight; he almost went blind in one eye. Over the years his vision worsened and he spent his last years in total blindness.

He died on 18 September 1783, at the age of 76, in St. Petersburg.

Leonhard Euler was born on 15 April 1707, in Basel, Switzerland, to Paul Euler and Marguerite Brucker in Basel. His father was a pastor of the Reformed Church while his mother was the daughter of a pastor, thus Euler was raised in a religious environment. He had two sisters.

His father taught the little boy mathematics, kindling in him a life long love for the subject. Leonhard’s father was friends with Johann Bernoulli, a prominent mathematician who would greatly influence the young boy.

He joined the University of Basel from where he received his Master of Philosophy in 1723. His father wanted him to become a pastor and thus Leonhard Euler began studying theology, Greek and Hebrew. But, he soon realized that theology did not interest him and that he wanted to pursue mathematics.

Leonhard Euler moved to Russia and served as a medical lieutenant in the Russian navy from 1727 to 1730. The son of Johann Bernoulli, Daniel, lived in Russia with whom Euler stayed.

He became professor of physics at the St Petersburg Academy of Sciences in 1730. Daniel, who held the senior chair at the mathematics department, left the job and Euler was appointed to this post in 1733.

He was a prolific author and had written numerous articles and textbooks. His textbook ‘Mechanica’ was published in 1736–37 in which he presented Newtonian dynamics in the form of mathematical analysis.

Another textbook, ‘Introductio in analysin infinitorum’ was out in 1748 in which he developed the concept of function in mathematical analysis. His works were of great significance to the field of modern analytic geometry and trigonometry.

In addition to mathematics he was also interested in astronomy and worked on developing a theory of lunar motion which involved the interactions of Sun, Moon, and Earth. He could only devise a partial solution which was published in 1753.

Euler is counted among the greatest mathematicians to have ever walked this earth. He had made tremendous contributions to the field of mathematics and is the only mathematician to have had two numbers named after him: Euler's Number in calculus, e, approximately equal to 2.71828, and the Euler–Mascheroni constant γ (gamma), approximately equal to 0.57721.

He helped develop the Euler–Bernoulli beam equation, which has widespread application in Civil and Mechanical Engineering.

Euler introduced several notational conventions. He was the first to write f(x) to denote the function, the Greek letter Σ for summations, and the letter 'e' for the base of the natural logarithm.