matlab-grid-generator/bin/griddata_fast.m

function zi = griddata_fast(delau,z,method)
%GRIDDATA_FAST Data gridding and surface fitting.
%   ZI = GRIDDATA_FAST(DEL,Z)
%
%   See also GRIDDATA_PREPROCESS

%   Clay M. Thompson 8-21-95
%   Copyright 1984-2001 The MathWorks, Inc. 
%   $Revision: 5.28 $  $Date: 2001/04/15 11:59:14 $

error(nargchk(2,3,nargin))

if nargin<3, method = 'linear'; end
if ~isstr(method), 
  error('METHOD must be one of ''linear'',''cubic'',''nearest'', or ''v4''.');
end


% Sort x and y so duplicate points can be averaged before passing to delaunay

switch lower(method),
  case 'linear'
    zi = linear(delau,z);
% case 'cubic'
%   zi = cubic(x,y,z,xi,yi);
% case 'nearest'
%   zi = nearest(x,y,z,xi,yi);
% case {'invdist','v4'}
%   zi = gdatav4(x,y,z,xi,yi);
  otherwise
    error('Unknown method.');
end
  
if nargout<=1, xi = zi; end


%------------------------------------------------------------
function zi = linear(del,z)
%LINEAR Triangle-based linear interpolation

%   Reference: David F. Watson, "Contouring: A guide
%   to the analysis and display of spacial data", Pergamon, 1994.

z = z(:).'; % Treat z as a row so that code below involving
            % z(tri) works even when tri is 1-by-3.
zi = sum(z(del.tri) .* del.w,2);

zi = reshape(zi,del.siz);

if ~isempty(del.out), zi(del.out) = NaN; end

%------------------------------------------------------------
1	function zi = griddata_fast(delau,z,method)
2	%GRIDDATA_FAST Data gridding and surface fitting.
3	% ZI = GRIDDATA_FAST(DEL,Z)
4	%
5	% See also GRIDDATA_PREPROCESS
6
7	% Clay M. Thompson 8-21-95
8	% Copyright 1984-2001 The MathWorks, Inc.
9	% $Revision: 5.28 $ $Date: 2001/04/15 11:59:14 $
10
11	error(nargchk(2,3,nargin))
12
13	if nargin<3, method = 'linear'; end
14	if ~isstr(method),
15	error('METHOD must be one of ''linear'',''cubic'',''nearest'', or ''v4''.');
16	end
17
18
19	% Sort x and y so duplicate points can be averaged before passing to delaunay
20
21	switch lower(method),
22	case 'linear'
23	zi = linear(delau,z);
24	% case 'cubic'
25	% zi = cubic(x,y,z,xi,yi);
26	% case 'nearest'
27	% zi = nearest(x,y,z,xi,yi);
28	% case {'invdist','v4'}
29	% zi = gdatav4(x,y,z,xi,yi);
30	otherwise
31	error('Unknown method.');
32	end
33
34	if nargout<=1, xi = zi; end
35
36
37	%------------------------------------------------------------
38	function zi = linear(del,z)
39	%LINEAR Triangle-based linear interpolation
40
41	% Reference: David F. Watson, "Contouring: A guide
42	% to the analysis and display of spacial data", Pergamon, 1994.
43
44	z = z(:).'; % Treat z as a row so that code below involving
45	% z(tri) works even when tri is 1-by-3.
46	zi = sum(z(del.tri) .* del.w,2);
47
48	zi = reshape(zi,del.siz);
49
50	if ~isempty(del.out), zi(del.out) = NaN; end
51
52	%------------------------------------------------------------