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a33039f58e Alis*0001 function zi = griddata_fast(delau,z,method)
0002 %GRIDDATA_FAST Data gridding and surface fitting.
0003 % ZI = GRIDDATA_FAST(DEL,Z)
0004 %
0005 % See also GRIDDATA_PREPROCESS
0006
0007 % Based on
0008 % Clay M. Thompson 8-21-95
0009 % Copyright 1984-2001 The MathWorks, Inc.
0010
4ec37fd829 Jean*0011 narginchk(2,3)
a33039f58e Alis*0012
0013 if nargin<3, method = 'linear'; end
0014 if ~isstr(method),
0015 error('METHOD must be one of ''linear'',''cubic'',''nearest'', or ''v4''.');
0016 end
0017
0018
0019 % Sort x and y so duplicate points can be averaged before passing to delaunay
0020
0021 switch lower(method),
0022 case 'linear'
0023 zi = linear(delau,z);
0024 % case 'cubic'
0025 % zi = cubic(x,y,z,xi,yi);
0026 % case 'nearest'
0027 % zi = nearest(x,y,z,xi,yi);
0028 % case {'invdist','v4'}
0029 % zi = gdatav4(x,y,z,xi,yi);
0030 otherwise
0031 error('Unknown method.');
0032 end
0033
0034 if nargout<=1, xi = zi; end
0035
0036
0037 %------------------------------------------------------------
0038 function zi = linear(del,z)
0039 %LINEAR Triangle-based linear interpolation
0040
0041 % Reference: David F. Watson, "Contouring: A guide
0042 % to the analysis and display of spacial data", Pergamon, 1994.
0043
0044 z = z(:).'; % Treat z as a row so that code below involving
0045 % z(tri) works even when tri is 1-by-3.
0046 zi = sum(z(del.tri) .* del.w,2);
0047
0048 zi = reshape(zi,del.siz);
0049
0050 if ~isempty(del.out), zi(del.out) = NaN; end
0051
0052 %------------------------------------------------------------
