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function zi = griddata_fast(delau,z,method) |
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%GRIDDATA_FAST Data gridding and surface fitting. |
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% ZI = GRIDDATA_FAST(DEL,Z) |
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% |
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% See also GRIDDATA_PREPROCESS |
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|
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% Based on |
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% Clay M. Thompson 8-21-95 |
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% Copyright 1984-2001 The MathWorks, Inc. |
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% $Revision: 1.1 $ $Date: 2004/06/04 15:50:52 $ |
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|
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% $Header: $ |
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% $Name: $ |
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|
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error(nargchk(2,3,nargin)) |
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|
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if nargin<3, method = 'linear'; end |
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if ~isstr(method), |
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error('METHOD must be one of ''linear'',''cubic'',''nearest'', or ''v4''.'); |
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end |
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|
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|
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% Sort x and y so duplicate points can be averaged before passing to delaunay |
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|
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switch lower(method), |
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case 'linear' |
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zi = linear(delau,z); |
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% case 'cubic' |
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% zi = cubic(x,y,z,xi,yi); |
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% case 'nearest' |
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% zi = nearest(x,y,z,xi,yi); |
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% case {'invdist','v4'} |
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% zi = gdatav4(x,y,z,xi,yi); |
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otherwise |
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error('Unknown method.'); |
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end |
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|
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if nargout<=1, xi = zi; end |
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|
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|
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%------------------------------------------------------------ |
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function zi = linear(del,z) |
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%LINEAR Triangle-based linear interpolation |
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|
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% Reference: David F. Watson, "Contouring: A guide |
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% to the analysis and display of spacial data", Pergamon, 1994. |
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|
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z = z(:).'; % Treat z as a row so that code below involving |
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% z(tri) works even when tri is 1-by-3. |
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zi = sum(z(del.tri) .* del.w,2); |
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|
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zi = reshape(zi,del.siz); |
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|
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if ~isempty(del.out), zi(del.out) = NaN; end |
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|
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%------------------------------------------------------------ |