| 释义 |
indicatrix|ɪndɪˈkeɪtrɪks|
[mod.L., fem. of indicator: see -trix. Cf. directrix.]
1. Geom. The curve in which a given surface is cut by a plane indefinitely near and parallel to the tangent-plane at any point; so called because it indicates the nature of the curvature of the surface at that point.
1841J. R. Young Math. Dissert. ii. 43 This evanescent curve, the limit of the intersections of the plane with the proposed surface, is that which Dupin calls the indicatrix. 1879Thomson & Tait Nat. Phil. I. i. §130 A plane parallel to the tangent plane and very near it cuts the surface in an ellipse, hyperbola, or two parallel straight lines, in the three cases respectively. This section, whose nature informs us as to whether the curvature be synclastic, anticlastic, or cylindrical, at any point, was called by Dupin the Indicatrix.
2. optical indicatrix: name given by L. Fletcher to a surface (sphere, spheroid, or ellipsoid) devised to indicate by its geometrical characters the optical characters of rays of light refracted through a crystal of any kind.
1892L. Fletcher (title) The Optical Indicatrix and the Transmission of Light in Crystals. Ibid. 20 To the surface of reference the term Optical Indicatrix may be assigned..The Indicatrix is identical in form with the ellipsoid of elasticity of various authors, the ellipsoid of polarisation of Cauchy, the ellipsoid of indices of MacCullagh, and the index-ellipsoid of Liebisch. |