Mathematician:Leonhard Paul Euler

Mathematician
Swiss mathematician and physicist who pioneered much of the foundation of modern mathematics.
 * Introduced much of the notation which is used today, including $e$ and the modern notation for trigonometric functions.
 * Proved Fermat's Little Theorem.
 * In $1783$, on the basis of considerable numerical evidence, conjectured the Law of Quadratic Reciprocity, which was eventually proven by in $1798$.


 * Proved the converse of the result known to, that if $2^p - 1$ is prime, then $2^{p-1} \left({2^p - 1}\right)$ is perfect. That is, proved that if $n$ is an even perfect number, then $n$ is of the form $2^{p-1} \left({2^p - 1}\right)$ where $p$ is prime. The results together are known as the Theorem of Even Perfect Numbers.

Possibly the most prolific writer of all time, in any field.

Was blind during the last 17 years of his life, but did not let that slow down his output.

Nationality
Swiss

History

 * Born: 15 April 1707, Basel, Switzerland
 * Died: 18 Sept 1783, St Petersburg, Russia

Geometry

 * Euler Triangle Formula

Analysis and Calculus

 * Euler-Maclaurin Summation Formula (with )
 * Euler Formula for Sine Function
 * Often credited with solving the Basel Problem, but it is believed that this was in fact solved by.
 * Euler-Darboux Equation (with )
 * Euler-Poisson-Darboux Equation (with and )


 * Euler's Reflection Formula

Complex Analysis

 * Euler's Formula
 * Euler's Identity

Number Theory

 * Euler's Criterion
 * Theorem of Even Perfect Numbers
 * Euler's Theorem
 * Euler-Binet Formula (with ) (also known as Binet's Formula)
 * Eulerian Integer (also known as Eisenstein Integer for )

Numerical Analysis

 * Euler Method
 * Improved Euler Method

Graph Theory

 * Handshake Lemma
 * The Bridges of Königsberg Problem
 * Euler Polyhedron Formula

Mechanics

 * Euler's Equations of Motion for Rotation of Rigid Body
 * Euler's Hydrodynamical Equation for Flow of Ideal Incompressible Fluid
 * Euler's Law for Bending of Elastic Beams
 * Euler's Critical Load for Buckling of Columns

Analysis and Calculus

 * Euler's Number (also known as Napier's Constant for )
 * Euler-Mascheroni Constant (with )
 * Cauchy-Euler Equation (with )
 * Eulerian Logarithmic Interval
 * Euler Multiplier

Number Theory

 * Euler Phi Function

Graph Theory

 * Euler Characteristic
 * Eulerian Circuit
 * Eulerian Graph
 * Semi-Eulerian Graph
 * Eulerian Trail

Set Theory

 * Euler Diagram

... and the list goes on.

Books and Papers

 * 1736: Solutio problematis ad geometriam situs pertinentis (The solution of a problem relating to the geometry of position) in which was given the Handshake Lemma and solution to the Bridges of Königsberg problem, possibly the first ever paper in graph theory.
 * 1736-37: Mechanica
 * 1739: Tentamen Novae Theoriae Musicae
 * 1740: Methodus Inveniendi Lineas Curvas
 * 1748: Introductio in Analysin Infinitorum
 * 1755: Institutiones Calculi Differentialis
 * 1765: Theoria Motus Corporum Solidorum
 * 1768-94: Institutionum Calculi Integralis

Linguistic Note
The correct pronunciation of Euler is Oi-ler, consistent with convention in Germanic languages.

Uninitiated English native speakers may be tempted to pronounce You-ler, but this is definitely wrong.

Consequently, noun phrases which begin with 's name would be preceded by "an" rather than "a", for example an Eulerian graph.

Critical View

 * Read Euler: he is our master in everything.


 *  He calculated without apparent effort, as men breathe, or as eagles sustain themselves in the wind.