| 释义 |
truncation|trʌŋˈkeɪʃən|
[ad. late L. truncātiōn-em, n. of action f. L. truncāre to truncate; cf. OF. troncacion (1495) in Godef.).]
1. The action of truncating; cutting short; maiming, mutilation. Also fig.
1579Fulke Heskins' Parl. 262 The alteration, falsification, and truncation of Tertullians wordes. 1611Cotgr., Troncation, a truncation, trunking, mutilation, cutting off. 1637Prynne Huntley's Breviate 48 Decreeing judgment of death, or truncation of members. a1682Sir T. Browne Tracts xiii. (1684) 204 Singular inhumanities in Tortures..The living truncation of the Turks. 1779–81Johnson L.P., Cowley Wks. II. 69 In the Davideis are some..verses left imperfect..in imitation of Virgil, whom he supposes not to have intended to complete them: that this opinion is erroneous, may be probably concluded, because this truncation is imitated by no subsequent Roman Poet [etc.]. 1903F. W. H. Myers Hum. Personality II. 301 If it [death] be..a sheer truncation of moral progress.
2. a. In scientific and technical use: The process of truncating, or condition of being truncated; diminution by or as by cutting off an end or point, so that the object terminates in a straight edge or plane surface instead; spec. in Cryst. replacement of an edge or solid angle by a plane face, esp. one equally inclined to the adjacent faces.
1796Kirwan Elem. Min. (ed. 2) II. 203 White Lead Ore..Occurs..crystalized in..prisms, or pyramids, with or without truncations. 1803H. J. Brooke Introd. Crystallogr. 86 The rhomboid being converted into a six-sided prism by the truncation of all its solid angles, or of its terminal solid angles and its lateral edges. 1853Kane Grinnell Exp. xlv. (1856) 416 The truncation of the muzzle..set their faces in almost perfect and human-like oval. 1861W. Pole in Macm. Mag. III. 184/2 The corresponding facet..formed by the truncation of the lower..pyramid, is..called the collet. 1874Lyell Elem. Geol. xxviii. 495 Similar..catastrophes have caused..the truncation..of some large cones in Java.
b. transf. The place or part where something is truncated.
1805–17R. Jameson Char. Min. (ed. 3) 117 When we observe on a fundamental figure, in place of an edge or angle, a small plane, such a plane is denominated a Truncation. 1853Phillips Rivers Yorksh. iv. 135 The ‘High Peak’..is at the truncation of an interior range of hills. 1897Hazlitt Suppl. Coinage European Cont. 29 This Portuguese piece has under the truncation of the bust the name of W. Wyon as the engraver.
c. Statistics. The cutting off of a frequency distribution at a certain value of the variate.
1937Yule & Kendall Introd. Theory of Statistics (ed. 11) vi. 103 We can picture it as a slightly skew distribution which has been cut off on the left owing to the inadmissibility of negative values of the variate. Discontinuous variates not infrequently give rise to this effect of truncation. 1952[see truncated ppl. a. 2 e].
d. The loss or removal of the upper horizon(s) of a soil by erosion.
1941H. Jenny Factors of Soil Formation v. 100 An example of widespread truncation is provided by the Cecil series of the Piedmont Plateau. 1972J. G. Cruickshank Soil Geogr. iv. 133 Loss of surface horizons by erosion (truncation) is more common in Oxisols [than in Spodosols].
e. Math. The cutting short of a numerical computation or expression before its natural end (if any). Usu. attrib. in truncation error.
1952D. R. Hartree Numerical Analysis x. 223 The solution of the set of equations..is not, of course, the solution of the partial differential equation on account of the truncation error of the approximation. 1968Fox & Mayer Computing Methods for Scientists & Engineers x. 205 For the fourth-order Runge-Kutta method the truncation error is the factor h5 multiplying a rather complicated expression involving derivatives of f(x, y). 1973[see rounding vbl. n.1 1 c]. |