MATLAB Function Reference    
griddatan

Data gridding and hypersurface fitting (dimension >= 2)

Syntax

Description

yi = griddatan(X, y, xi) fits a hyper-surface of the form to the data in the (usually) nonuniformly-spaced vectors (X, y). griddatan interpolates this hyper-surface at the points specified by xi to produce yi. xi can be nonuniform.

X is of dimension m-by-n, representing m points in n-D space. y is of dimension m-by-1, representing m values of the hyper-surface (X). xi is a vector of size p-by-n, representing p points in the n-D space whose surface value is to be fitted. yi is a vector of length p approximating the values (xi). The hypersurface always goes through the data points (X,y). xi is usually a uniform grid (as produced by meshgrid).

[...] = griddatan(...,'method') defines the type of surface fit to the data, where 'method' is one of:

'linear'
 Tessellation-based linear interpolation (default)
'nearest'
 Nearest neighbor interpolation

All the methods are based on a Delaunay tessellation of the data.

Algorithm

The griddatan methods are based on a Delaunay triangulation of the data that uses Qhull [2]. This triangulation uses the Qhull joggle option ('QJ'). For information about Qhull, see http://www.geom.umn.edu/software/qhull/. For copyright information, see http://www.geom.umn.edu/software/download/COPYING.html.

See Also

delaunayn, griddata, griddata3, meshgrid

Reference

[1]  Barber, C. B., D.P. Dobkin, and H.T. Huhdanpaa, "The Quickhull Algorithm for Convex Hulls," ACM Transactions on Mathematical Software, Vol. 22, No. 4, Dec. 1996, p. 469-483. Available in HTML format at http://www.acm.org/pubs/citations/journals/toms/1996-22-4/p469-barber/ and in PostScript format at ftp://geom.umn.edu/pub/software/qhull-96.ps.

[2]  National Science and Technology Research Center for Computation and Visualization of Geometric Structures (The Geometry Center), University of Minnesota. 1993.


  griddata3 gsvd