| 释义 |
▪ I. † summation1 Obs.
Also 5 somac(i)on.
[a. OF. som(m)acion, f. sommer to summon.]
Summons.
1471Caxton Recuyell (Sommer) 222 Perseus..sente danus vnto the kynge prycus to somene hym that he shold yelde the royame vnto kynge Acrisius. Danus wente to Arges. And accomplisshed the somacion. c1477― Jason 57 b, Whan Iason vnderstode the somacon that the two damoiselles made he was sore abasshid. 1864D. G. Mitchell Sev. Stor. 7 The admiring spirit with which..I yielded my pence to his impetuous summation.
▪ II. summation2|sʌˈmeɪʃən|
[ad. mod.L. summātio, -ōnem, n. of action f. med.L. summāre to sum. Cf. F. sommation.]
1. Math. The process of finding the sum of a series. Also in fig. context.
1760Phil. Trans. LI. 553 Any branch of it [sc. the analytic art] that relates to the summation of series. 1842Penny Cycl. XXIII. 267/1 The summation of a finite number of terms of a series. 1860Sylvester Math. Papers (1908) II. 228 The (σ)r meaning merely the sign of summation r times repeated. 1874Stubbs Const. Hist. I. i. 4 The constitutional history of France is thus the summation of the series of feudal development in a logical sequence. 1885Watson & Burbury Math. Th. Electr. I. 167 If the system consist only of conductors on which the charges are e1, e2, &c., we have E = ½σVe, σ denoting summation for all the conductors.
2. The adding up of numbers; casting up an account; an addition sum.
1816Scott Antiq. xxii, It amounts..to eleven hundred and thirteen pounds, seven shillings, five pennies, and three-fourths of a penny sterling—But look over the summation yourself. 1854H. Miller Sch. & Schm. xxiii. (1858) 512, I never acquired the facility, in running up columns of summations, of the early-taught accountant. 1883Nonconf. & Indep. 28 Dec. 1168/3 A summation made up by me to the end of last year.
3. a. The addition of mensurable quantities (distance, time, etc.), now esp. such addition in an electronic device.
1860Tyndall Glac. i. xi. 81 The summation of distances twenty paces each must finally place us at the top. 1914Petrie in Anc. Egypt 32 A summation of years. 1962M. G. Hartley Introd. Electronic Analogue Computers iii. 23 An arrangement for the summation of three voltages. 1977J. G. Graeme Designing with Operational Amplifiers vii. 175 This characteristic makes possible signal summation and subtraction through the simple connection of summing or differencing resistors to the amplifier inputs. 1981F. W. Hughes Op Amp Handbk. viii. 206 The output signal may be a direct mathematical summation of the input signals or may include a determined amount of gain.
b. The process or effect by which repeated or multiple nerve impulses can produce a response that each impulse alone would fail to produce.
1877M. Foster Physiol. iii. v. (1878) 471 The central mechanism..being thrown into activity through a summation of the afferent impulses reaching it. 1883Nature XXVII. 439 This relation of the contractile tissue to stimuli is usually expressed by saying that the tissue has the power of summation. 1889Lancet 3 Aug. 203/1 A summation of the stimuli appears to go on in the cells. 1956A. C. Guyton Textbk. Med. Physiol. v. 45/1 If impulses occur too far apart in time..temporal summation will not occur. 1979Spence & Mason Human Anat. & Physiol. xi. 293 During spatial summation, nerve impulses in many different stimulatory presynaptic cells travelling to a single postsynaptic cell may all arrive at the postsynaptic cell very close together in time.
c. Psychol. Cumulative action or effect (see quots.).
1921E. J. Kempf Psychopathol. i. 62 The tendency to suppress our affections may accumulate; that is, a summation of the repressing or suppressing egoistic wishes may occur. 1924J. Riviere et al. tr. Freud's Coll. Papers I. 95 An assumption which is not improbable in itself—namely, that a noxia such as coitus interruptus attains its effect by summation. According to the disposition of the person..a longer or shorter time will be required before the effect of this summation becomes evident. 1955J. Strachey et al. tr. Freud's Compl. Psychol. Wks. II. ii. 174 Even a hysteric can retain a certain amount of affect that has not been dealt with; if, owing to the occurrence of similar provoking causes, that amount is increased by summation to a point beyond the subject's tolerance, the impetus to conversion is given.
4. The computation of the aggregate value of conditions, qualities, etc.; summing-up.
1836Lytton Athens (1837) I. 455 Valour seems to have been for his [Miltiades'] profound intellect but the summation of chances. 1856Dove Logic Chr. Faith v. i. 262 Our conception of duty is either ‘Yea’, or ‘Nay’ without.. summations of advantages. 1908Daily Chron. 26 Feb. 3/3 Such is Mr. Wyndham's summation of Scott.
5. The aggregate or sum-total; the resultant or product.
1840Carlyle Heroes i. (1872) 20 They are not one coherent System of Thought; but properly the summation of several successive systems. 187919th Cent. Sept. 500 He is the summation of Hebraism and Hellenism. 1885Manch. Exam. 13 July 6/1 Mr. Harrison..regards God as the summation of Humanity.
6. attrib. and Comb., as summation network, summation theory; summation check Computers = sum check s.v. sum n.1 14; summation tone, Acoustics [G. summationston (Helmholtz)] = summational tone (see tone n. 2).
1954Computers & Automation Dec. 22/1 Summation check. 1969Jordain & Breslau Condensed Computer Encycl. 498 One weakness of the summation check is its inability to detect transposed digits.
1968D. Eadie Introd. Basic Computer xv. 347 In most analog computers the summation network is combined with an operational amplifier.
1901E. B. Titchener Exper. Psychol. I. ii. 90 If we are not satisfied with this ‘summation’ theory, we may..suppose that the gaps in sensation are filled out by association.
1867Tyndall Sound vii. 285 Resultant tones are of two kinds... The former are called difference tones, the latter summation tones. 1875Encycl. Brit. I. 118/2 [Helmholtz] was led..to surmise the formation of summation-tones by the interference of two loud primaries. |