释义 |
GradientThe gradient is a Vector operator denoted and sometimes also called Del or Nabla.It is most often applied to a real function of three variables , and may be denoted
 | (1) |
For general Curvilinear Coordinates, the gradient is given by
 | (2) |
which simplifies to
 | (3) |
in Cartesian Coordinates.
The direction of is the orientation in which the Directional Derivative has the largest value and is the value of that Directional Derivative. Furthermore, if , then the gradientis Perpendicular to the Level Curve through if and Perpendicular to the levelsurface through if .
In Tensor notation, let
 | (4) |
be the Line Element in principal form. Then
 | (5) |
For a Matrix ,
 | (6) |
For expressions giving the gradient in particular coordinate systems, see Curvilinear Coordinates.See also Convective Derivative, Curl, Divergence, Laplacian, Vector Derivative References
Arfken, G. ``Gradient, '' and ``Successive Applications of .'' §1.6 and 1.9 in Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, pp. 33-37 and 47-51, 1985. |