单词 | parameter |
释义 | parametern. I. Technical uses. 1. Geometry. (The length of) a chord passing through the focus of a conic section which is bisected by a specified diameter (line parallel to the transverse or major axis); spec. the latus rectum, the chord bisected by and perpendicular to the transverse axis. ΘΚΠ the world > relative properties > number > geometry > line > [noun] > specifically in conic sections parameter1656 polar1848 1656 T. Hobbes Six Lessons iii. 27 in Elements Philos. As much in vain..as seek for the Focus, or Parameter of the Parabola of Dives and Lazarus. 1704 J. Harris Lexicon Technicum I Parameter, by some..called the Latus Rectum of a Parabola, is a Third Proportional to the Abscissa and any Ordinate. 1798 C. Hutton Course Math. II. 98 The Parameter of any diameter, is a third proportional to that diameter and its conjugate. 1816 tr. S. F. Lacroix Elem. Treat. Differential & Integral Calculus 401 If..the parameter of a parabola be made to vary, a series of parabolas will be obtained. 1891 C. Taylor Elem. Geom. Conics (ed. 7) iii. §17 The Parameter of any diameter of a parabola is the focal chord which it bisects: thus the latus rectum is the parameter of the axis. 1995 Math. Mag. 68 367 We see that the slope of the common tangent is the (negative) cube root of the quotient of the parameters of the parabolas. 2. Astronomy. Each of a set of numerical quantities, typically six, that jointly specify the orbit of a planet, comet, or other body; = element n. 7a. Usually in plural. ΘΚΠ the world > the universe > cosmology > science of observation > astronomical calculation > [noun] > part argumentc1405 astronomicalsa1690 element1788 parameter1829 perturbative function1856 luminosity function1924 Hubble constant1933 Oort constant1941 1829 Encycl. Metrop.: Mixed Sci. I. Index Variation of Parameters. 1837 Abstr. Papers Royal Soc. 1830–37 3 111 The other method is that of the variation of parameters (developed by Lagrange), according to which the planet..is conceived to be moving in an ellipse, and the alterations are investigated which the elements of this ellipse must continually undergo. 1840 Penny Cycl. XVII. 240/1 The parameters of the orbits are now generally called their elements. 1906 Trans. Amer. Math. Soc. 7 576 Happel has shown that they [sc. the solutions to an equation] converge for the values of these parameters which belong to the moon's variational orbit. 1963 R. H. Merson in M. Roy Dynamics of Satellites 83 The values of the six basic elements at a given time..are determined from a set of observations by a differential correction technique... In addition to the estimates of the orbital parameters, estimates of their variances and covariances are also determined. 1967 Technol. Week 20 Feb. 13 Orbital parameters were apogee—817·2 mi.; perigee—128 mi.; inclination—48·4 degrees, and period 100·3 minutes. 1992 S. P. Maran Astron. & Astrophysics Encycl. 128/1 In 1818 the German mathematician Johann F. Encke attempted to calculate the orbital parameters of a comet discovered by the great observer Jean L. Pons. 3. Mathematics. a. A quantity which is fixed (as distinct from the ordinary variables) in a particular case considered, but which may vary in different cases; esp. a constant occurring in the equation of a curve or surface, by the variation of which the equation is made to represent a family of such curves or surfaces (cf. quot. 1816 at sense 1). Also (Computing): a quantity whose value is specified when a routine is to be performed. ΘΚΠ the world > relative properties > number > mathematical number or quantity > [noun] > particular qualities > constant constant1832 parameter1833 invariable1864 the world > relative properties > number > algebra > [noun] > expression > parameter parameter1833 1833 Abstr. Papers Royal Soc. 1815–30 2 230 By varying a certain parameter in the equation of these curves, other forms, having infinite branches and points of contrary flexure, arise. 1844 G. Boole in Philos. Trans. (Royal Soc.) 134 234 Substitute this value of u in the original equation.., regarding A, B, C..as variable parameters. 1885 C. Leudesdorf tr. L. Cremona Elements Projective Geom. 63 This anharmonic ratio is called the coefficient or parameter of the homology. 1948 Proc. Royal Soc. A. 195 286 In order to make the standard routines as general as possible they are usually constructed with a number of parameters. 1969 Computers & Humanities 3 278 Thus input parameters were included to specify page width and length, and the dictionary was photo-offset. 1973 P. W. Murrill & C. L. Smith Introd. Computer Sci. 585 Through the use of arguments and parameters, subroutines and functions can be used throughout a program to perform identical operations upon many different data items. 1990 Q. Jrnl. Mech. & Appl. Math. 43 440 For the above values of the relevant parameters, the system of equations (32) are solved for amplitude ratios by using the Gauss elimination method for different angles of incidence varying from 0° to 90°. b. An independent variable in terms of which each coordinate of a point of a curve, surface, etc., is expressed, independently of the other coordinates. ΘΚΠ the world > relative properties > number > geometry > geometric space > [noun] > division or marking of > axis > of coordinates > co-ordinate > parameter parameter1855 1855 Proc. Royal Soc. 7 199 Each order of terms [contains]..four kinds of trigonometric functions, multiplied by six exponential functions of the third co-ordinate, whose parameters are the roots of an equation of the sixth order. 1873 G. Salmon Treat. Higher Plane Curves (ed. 2) viii. 317 The coordinates x′, y′, z′ are..expressible as quadric functions of a parameter θ. 1907 J. H. Grace & F. Rosenberg Coordinate Geom. xvi. 220 If we can find simple expressions for the coordinates of points on a conic in terms of one variable quantity, a point on the curve may be looked on as determined by a definite value of the variable, the variable being usually called the parameter. 1991 J. Hunt & D. Sturge in C. Bondi New Applic. Math. iv. 94 Once the surface of an object is represented as a patchwork, and the coordinates of each point on the surface are known in terms of the parameters u and v, the engineering designer can use the information in many ways. 4. Crystallography. The length of the intercept made on any of the axes of a crystal by a given face, expressed in convenient arbitrary units. Usually in plural. ΚΠ 1839 W. H. Miller Crystallogr. 2 The parameters are the portions of the axes cut off by a given face. 1895 N. Story-Maskelyne Crystallogr. ii. §18 The ratios a:b:c of the intercepts [on the axes] of some one plane chosen as a standard or parametral plane are termed the parametral ratios or parameters of the system as referred to the axes X, Y, Z. 1954 J. F. Kirkaldy Gen. Princ. Geol. xi. 134 If we take one of the faces as the unit face and regard its intercepts as units of measurement or parameters, then we find that the intercepts made by the face of different inclination can be expressed in simple terms of the parameters, i.e. half, equal to, twice that of the unit face, etc. 5. Any of several numerical quantities that can be used jointly to characterize an electrical circuit or network. ΘΚΠ the world > matter > physics > electromagnetic radiation > electricity > electrical engineering > [noun] > network > characterizing quantity parameter1911 the world > matter > physics > electromagnetic radiation > electronics > electronic phenomena > electronic circuit > [noun] > network configurations > quantity characterizing parameter1962 1911 Trans. Amer. Inst. Electr. Engineers 30 885 The impedances required to make a normal type of network of the requisite number of parameters equivalent to the given network under specified conditions of operation. 1930 T. E. Shea Transmission Networks & Wave Filters iii. 71 Any network having one pair of input and one pair of output terminals may be completely represented..by a T network (or network having any form providing at least three independent parameters) as far as external current and voltage conditions are concerned. 1962 J. H. Simpson & R. S. Richards Physical Princ. Junction Transistors v. 82 The h's define the following circuit parameters: h11 = hi = input impedance with output short-circuited.., h12 = hr = reverse voltage ratio with input open-circuited. 1998 SIAM Rev. 40 351 Consider a transmission line, where the distributed parameters are g, shunt conductance; c, shunt capacitance; r, series resistance; and l, series inductance. 6. Statistics. A numerical characteristic of a population, as distinguished from a statistic obtained by sampling. ΘΚΠ the world > relative properties > number > probability or statistics > [noun] > population > numerical characteristic of parameter1920 1920 Proc. National Acad. Sci. U.S.A. 6 427 The problem mathematically is to find a single parameter which will fully describe so complex a curve as that of the age distribution of a population. 1939 A. E. Treloar Elements Statist. Reasoning x. 130 The true sampling error of each sample mean and standard deviation, so far as those statistics form estimates of the corresponding parameters, may be expressed as [etc.]. 1975 D. L. Harnett & J. L. Murphy Introd. Statistical Anal. i. 5 The numerical characteristics of a sample are used to estimate the parameters of the parent population from which this sample was drawn. 7. a. Music. Any more or less quantifiable feature (as pitch, rhythm, etc.) of a musical context; esp. such a feature undergoing a systematic sequence of modifications in a serialist work. ΚΠ 1968 Listener 19 Sept. 377/1 By means of chance operations..the parameters of pitch (and therefore form) were removed from the domains of the composer's will and taste. 1976 J. Peyser Boulez 107 [Robert] Beyer introduced the word ‘parameter’ into music, borrowing it from mathematics apparently to give weight and dignity to what otherwise would be called an element or dimension. The parameters of a musical tone are its pitch, rhythm, dynamics, articulation, texture and register, each of which was to be subjected to permutation. 1980 New Grove Dict. Music XIV. 178/2 It is difficult to see how the musical application of ‘parameter’ is an interpretation of the mathematical meaning. 1993 R. Walser Running with Devil 41 Of all musical parameters, timbre is least often analyzed. b. Any of the user-controlled settings which determine the characteristics of the sound produced by a synthesizer, electronic instrument, etc. ΘΚΠ society > leisure > the arts > music > musical instrument > other musical instruments > [noun] > electronic > electronic effects and devices > settings parameter1983 1980 New Grove Dict. Music XIV. 178/2 While in synthesized music certain parameters of a note must be specified, the extension of the term to less quantifiable areas is unhelpful.] 1983 Softline May–June 18/2 The top nibble of AUDCX contains the distortion parameter for the channel, and the bottom nibble contains the volume information. 1989 Rhythm Apr. 31/2 Other parameters allow you to select the Instrument's velocity response curve (1-8), output assignment..and voicing. 1998 Making Music Apr. 37/1 Guitarists who like to plug in and play, not spend hours scrolling through endless parameters trying to find a decent sound. II. Extended uses. 8. Any distinguishing or defining characteristic or feature, esp. one that may be measured or quantified; an element or aspect of something; (more widely) a boundary or limit. ΘΚΠ the world > relative properties > wholeness > incompleteness > part of whole > [noun] > constituent part or component > aspect of an abstract entity visagec1374 sidea1393 respecta1398 facet1808 prong1859 parameter1927 dimension1929 the world > relative properties > kind or sort > individual character or quality > quality of being special or restricted in application > quality of being restricted or limited > [noun] > limit markOE measurea1375 bound1393 sizec1420 banka1425 limita1425 limitationa1475 stint1509 within one's tether?1523 confine1548 tropic?1594 scantling1597 gauge1600 mound1605 boundalsa1670 meta1838 parameter1967 1927 Proc. Royal Soc. 1926–7 A. 113 642 In the case of phenacite, the symmetry of the structure imposes no limitations on the position of the seven atoms in the molecule, so that twenty-one parameters are required to define the structure. 1939 M. J. Brevoort & U. T. Joyner Cooling on Front of Air-cooled Engine Cylinder (NACA Techn. Rep. No. 674) 1/1 These results are introductory to the study of front cooling and show the general effect of the several test parameters. 1962 Rep. Comm. Broadcasting 1960 335 in Parl. Papers 1961–2 (Cmnd. 1753) X. 259 Many Western European countries..are considering whether there would be advantage in using..the technical parameters they already use for 625-line standards in the 7 Mc/s channels of Bands I and III. 1965 Listener 9 Dec. 943/2 There remains the bulk of those for whom politics is a parameter of life rather like the weather. 1967 Economist 16 Dec. 1157/1 A second, even bigger generator of 1,300 MW was also contracted for... With these orders, practically every existing parameter of power generating practice has been exceeded. 1971 Jrnl. Gen. Psychol. 84 18 Three phenomena corresponding to the three major parameters of color—brightness, hue, and saturation. 1975 Times 14 Oct. 15/4 The considerable element of indeterminacy which exists within the parameters of the parole system. 1983 H. Evans Good Times, Bad Times i. 23 By the end of the series we had broken every single parameter—and given the public the right to judge. 1995 Online Access Sept. 10/2 DWANGO features a free online chat room where users can meet, decide which game to play and set up teams and other game play parameters. This entry has been updated (OED Third Edition, June 2005; most recently modified version published online March 2022). < n.1656 |
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