[dFx,dFy] = TRIGRADIENT(TRI,X,Y,Z) or TRIGRADIENT(TRI,X,Y,Z,'vertex') returns numerical gradients of the function z = F(x,y), dFx = dF/dx and DFy = dF/dy at the vertices of the triangles specified in TRI. dFx and dFy are column vectors having the same number of elements as X, Y, and Z.
TRI, X, Y, and Z define a triangulation where the triangles are defined by the M-by-3 face matrix TRI, such as that returned by DELAUNAY. Each row of TRI contains indices into the X, Y, and Z vertex vectors to define a single triangular face.
The gradients are computed by an inverse distance method, whereby the gradient at a vertex is computed by weighting the gradients of each triangle face sharing the vertex in proportion to the inverse distance from the center of each triangle to the vertex.
[dFx,dFy] = TRIGRADIENT(TRI,X,Y,Z,'face') returns the numerical gradients that are constant over each triangle face. In this case, dFx and dFy are column vectors having M = size(TRI,1) elements.
· MATLAB Release: R2006a