# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 6 Search : Euler
 Euler   اویلر   EulerFr.: Euler   Leonhard Euler (1707-1783), the eminent Swiss mathematician, physicist, and astronomer. Euler equation   هموگش ِ اویلر   hamugeš-e EulerFr.: équation d'Euler   In → fluid mechanics, one of a set of → differential equations that govern the motion of a → compressible, → inviscid fluid. Euler equations correspond to the → Navier-Stokes equations with zero → viscosity.→ Euler; → equation. Euler line   خط ِ اویلر   xatt-e EulerFr.: droite d'Euler   In any → triangle, the straight line on which always lie the → centroid, → circumcenter, and → orthocenter.→ Euler; → line. Euler's broken line   خط ِ شکسته‌ی ِ اویلر   xatt-e šekaste-ye EulerFr.: ligne brisée   The line drawn in a coordinate plane connecting the approximate values of the solution of a → first-order differential equation.→ Euler; → broken line. Euler's formula   دیسول ِ اویلر   disul-e EulerFr.: formule d'Euler   A formula which expresses an → exponential function with an → imaginary number  → exponent in terms of → trigonometric functions: eiθ = cos θ + i sinθ, e-iθ = cos θ - i sinθ, cosθ = (eiθ + e-iθ)/2, sinθ = (eiθ - e-iθ)/2i. In the particular case of θ = π, Euler's formula becomes: eiπ + 1 = 0, which is considered by many mathematicians to be the most elegant mathematical equation. → mathematical elegance.→ Euler; → formula. Eulerian method   روش ِ اویلری   raveš-e EuleriFr.: méthode eulérienne   Fluid mechanics: A method in which the changes in the physical properties of the fluid, such as velocity, acceleration, and density are described at a fixed point in space occupied by the fluid. Compare with → Lagrangian method.→ Euler; → method.