Fr.: fonction source
For a radiating material, the ratio of emissivity to opacity.
Fr.: fonction spline
A function consisting of several segments, usually → polynomials, joined smoothly together at specific points with an explicitly stated degree of accuracy. Spline functions are used to approximate a given function on an interval.
From East Anglian dialect, maybe related to O.E. splin and to modern splint. A spline was originally a slat or a thin strip of wood. A later meaning was "a long, thin, flexible strip used as a guide for drawing arcs of curves;" → function.
stellar creation function
karyâ-ye âfarineš-e setâregân
Fr.: fonction de création stellaire
The number of stars born per unit area in the mass range log M to log M + d log M during the time interval t to t + dt. The integration of the creation function over time gives the → present-day mass function (Miller & Scalo, 1797, ApJSS 41, 513).
Fr.: fonction échelon
Math.: A function f of a real variable defined on an interval [a,b] so that [a,b] can be divided into a finite number of sub-intervals on each of which f is a constant. The graph of a step function is a series of line segments resembling a set of steps.
Step, from M.E. steppen, O.E. steppan; cf. Du. stap, O.H.G. stapfo, Ger. stapfe "footprint;" → function.
Fr.: fonction totale
A function whose value is defined for all possible input values.
Fr.: fonction transcendante
A function which is not → algebraic. For example y = cosx, y = 10xx.
Fr.: fonction de transfert
The mathematical relationship between the output of a control system and its input: for a linear system, it is the Laplace transform of the output divided by the Laplace transform of the input under conditions of zero initial-energy storage.
Fr.: fonction de transition
Fr.: fonction circulaire, ~ trigonomtérique
A function of an angle, one of six functions (sine, cosine, tangent, cotangent, secant, and cosecant) that represent ratios of sides of right triangles. Also called circular function.
Fr.: fonction de vérité
Fr.: fonction non bornée
The function y = f(x) in a given range of the argument x if there is no number M such that for all values of x in the range under consideration the inequality | f(x) | ≤ M will be fulfilled. → bounded function.
Fr.: fonction vectorielle
A function whose value at each point is n-dimensional, as compared to a scalar function, whose value is one-dimensional.
karyâ-ye diyâri, ~ padidâri
Fr.: fonction de visibilité
The Fourier transform of a source's brightness distribution, weighted by the characteristics of the interferometer's antennas.
Fr.: fonction d'onde
In → quantum mechanics, the function of space and time that satisfies → Schrodinger equation. The square of the modulus of its amplitude at any point represents the probability of finding a particle there.
→ wave; → function.
Fr.: fonction fenêtre
A function whose value is zero outside a given interval. Applications of window functions include signal filtering and spectral analysis. The various types of windw functions include: → rectangular window, cosine window, triangular window, Gaussian window, Hanning window, and so on.
Fr.: travail d'extraction
The least amount of energy required to remove an electron from the surface of a solid, to a point just outside the solid where the electron has zero kinetic energy. See also → photoelectric effect.