On April 15, 1707, the Swiss mathematician Leonhard Euler was born in Basel (Switzerland).

On this day (April 15), 1707, the Swiss mathematician Leonhard Euler was born in Basel (Switzerland).
Leonhard Euler is undoubtedly the most original mathematician of his century and the most prolific of all time. He made fundamental contributions in many areas of mathematics: Geometry, Number Theory, Algebra, Mechanics, Astronomy, etc. But they probably stand out above all else in his mathematical work his contributions to Analysis.
Euler's production is monumental. In 1911, the Swiss Academy of Sciences began publishing a definitive collection of Euler's works titled Opera Omnia; over eighty volumes!
Euler worked in practically all areas of mathematics: geometry, calculus, trigonometry, algebra, theory of numbers, as well as continuum physics, lunar theory and other areas of physics. Additionally, he made relevant contributions to mathematical logic with his set diagram .
His work reaches out to embrace;

Mathematical notation

Euler introduced and popularized several conventions regarding notation in mathematical writings in his numerous;

• f(x) to designate the function f applied to the abstract x
• e as the base of the natural or natural logarithm
• Σ as symbol of summations
• to refer to the imaginary unit
• .....

Analysis

Although some of his mathematical proofs are not acceptable by modern standards of mathematical rigor, it is true that his ideas led to great advances in that field.

The number e

Euler defined the mathematical constant known as number as that real number such that the value of the derivative (the slope of the tangent line) of the function = x at point is exactly 1

Number Theory

Much of Euler's early work in number theory is based on the work of Pierre de Fermat. Euler developed some of the ideas of this French mathematician but also discarded some of his conjectures.

Graph theory and geometry

In 1736, Euler solved the problem known as the Königsberg bridge problem. Euler managed to prove mathematically that there is no solution. This solution is considered the first theorem of graph theory and planar graphs.

Applied Mathematics

Some of Euler's greatest successes were in solving real-world problems through mathematical analysis, in what is known as applied mathematics.

In 1739 he wrote his work Tentamen novae theoriae musicae, hoping to incorporate the use from mathematics to music theory. It was considered to be "too mathematical for musicians and too musical for mathematicians".

Physics and astronomy

Euler helped develop the equation of the elastic curve, which became the mainstay of engineering

Logic

Euler is credited with using closed curves to illustrate reasoning syllogistic (1768).

Architecture and engineering

Euler spawned a new branch of engineering with his work on the critical loading of columns

As a curiosity, comment that his book "letters to a German princess" resulted from the compilation of a series of 234 letters written by Euler and is considered one of the first and most popular popular science books in Europe.

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- Dad, can you help me?
- sure son, tell me
- what is the number e?
-e?
- yes, the number e
- huh?
- yes! Euler's e-number!
- of course! Euler's e-number!
- if it had been the number p, it would be from Pablo