| 释义 |
developable, a. and n.|dɪˈvɛləpəb(ə)l|
[f. prec. vb. + -able: in mod.F. développable.]
A. adj.
a. Capable of being developed or of developing.
1835R. F. Wilson in Newman's Lett. (1891) II. 139 Principles..only developable under one form. 1865Wilkins Pers. Names Bible 360 It is the nature of symbolical names used sacramentally to possess a developable significance. 1875Whitney Life Lang. xiv. 292 Instinctive gesture, developable into a complete system of expression. 1879Jevons in Contemp. Rev. Nov. 537 It now becomes a moving and developable moral sense.
b. Math. (a) Of a function or expression: Capable of being expanded. (b) Of a curved surface: Capable of being unfolded or flattened out: (see develop v. 1 b).
1816tr. Lacroix' Diff. & Int. Calc. 479 If f(Δ) be a function of Δ developable in a series of powers of Δ..then [etc.]. 1840Lardner Geom. 247 Two developable surfaces will intersect in a right line, if the right lines, by the motion of which they are generated, coincide in any one position. 1865W. S. Aldis Solid Geom. ix. §146 Ruled surfaces in which consecutive generating lines lie in one plane are called developable surfaces, while all other ruled surfaces are called skew surfaces. 1866Proctor Handbk. Stars 16 note, In reality..even such narrow strips of a globe are not developable, and the chord and arc of five degrees are not equal, as they are assumed to be.
c. Photogr. Capable of being developed (see develop v. 5 b).
1878Abney Treat. Photogr. iv. 30 An exposure in the camera to produce a developable image would have to be very prolonged. 1907Westm. Gaz. 26 Oct. 13/2 They take only a short time to produce a developable condition in the emulsion. 1958Amateur Photographer 31 Dec. 393/2 The need for one quantum (the unit of energy) to strike each grain of silver to make it developable.
B. n. (Math.) A developable surface; a ruled surface in which consecutive generators intersect.
1874Salmon Geom. three Dimens. §305 The locus of points where two consecutive generators of a developable intersect is a curve..which is called the cuspidal edge of that developable. |