| 释义 |
logarithmic, a. (and n.) Math.|lɒgəˈrɪθmɪk, -ɪð-|
[f. logarithm + -ic. Cf. F. logarithmique.]
A. adj.
a. Of or pertaining to logarithms. Also in logarithmic sine, tangent, secant, etc., used (somewhat incorrectly) to denote the logarithm of the function named; opposed to natural.
logarithmic amplifier Electr., an amplifier which produces an output in logarithmic proportion to the input; logarithmic curve (or logarithmic line), a curve having its ordinates in geometrical progression and its abscissas in arithmetical progression, so that the abscissas are the logarithms of the corresponding ordinates; logarithmic decrement: see decrement 2 b; logarithmic ellipse, logarithmic hyperbola (see quots. 1851); logarithmic phase Biol., the period during which the population of a culture of bacteria increases exponentially with time; logarithmic spiral, a spiral which intersects all its radiants at the same angle.
1698J. Keill Exam. Th. Earth (1734) 243 The Applicate of the Logarithmick curve DEF. 1706W. Jones Syn. Palmar. Matheseos 261 The Curve describ'd by their Intersection is called the Logarithmic Line... A Point from the Extremity thereof, moving towards the Centre with a Velocity decreasing in a Geometric Progression, will generate a Curve called the Logarithmic Spiral. 1752Robertson in Phil. Trans. XLVIII. 100 Now subtract the logarithmic versed sines of such degrees..as are intended to be put on the scale, from the logarithm versed sine of 180°. 1797Encycl. Brit. II. 423/2 Constructing logarithmic tables to facilitate their [sc. astronomers] calculations. 1851J. Booth Elliptic Integrals Pref., I have named them [two curves] the spherical parabola, and the logarithmic ellipse... The latter [may be traced] on a paraboloid of revolution. Ibid. 159 If a right cylinder, standing on a plane hyperbola as a base, be substituted for the elliptic cylinder, the curve of intersection with the paraboloid may be named the logarithmic hyperbola. 1878Clifford Elem. Dynamic i. 78 A point is said to have logarithmic motion on a straight line when the distance from a fixed point on the line is equally multiplied in equal times. 1881Maxwell Electr. & Magn. II. 347 Another point which moves with uniform angular velocity in a logarithmic spiral. 1914Jrnl. Hygiene XIV. 260 This selected strain holds the field during the second or logarithmic phase. 1938Logarithmic phase [see log phase s.v. log n.3 and a. 2]. 1954C. P. Snow New Men vi. 101 There was one of those counters whose ticking I had come to expect in any Barford laboratory; there was a logarithmic amplifier, a D.C. amplifier..which would give a measure..of the ‘neutron flux’. 1957C. Wu in C. F. Bonilla Nucl. Engin. iv. 128 When a wide range of the neutron flux, as much as six to eight decades, is to be measured, a logarithmic amplifier must be used. 1971J. S. Hough et al. Malting & Brewing Sci. xviii. 480 The next stage is the dividing of the cells at a constant rate, referred to as the ‘exponential phase’ or ‘logarithmic phase’.
b. Pertaining to the logarithmic curve.
1875R. F. Martin tr. Havrez' Winding Mach. 17 A round steel rope of logarithmic form..would weigh only 1594 kilogs.
B. n. = logarithmic curve or line.
1753Chambers Cycl. Supp. s.v., Let AVD be a logarithmic, and its ordinates AB, VC, DQ. 1797Brougham in Phil. Trans. LXXXVIII. 396 The common logarithmic has its subtangent constant. |