Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / optiminterp-0.3.3 / example_optiminterp.m

diff --git a/octave_packages/optiminterp-0.3.3/example_optiminterp.m b/octave_packages/optiminterp-0.3.3/example_optiminterp.m
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+%% Copyright (C) 2008 Alexander Barth
+%%
+%% This program is free software; you can redistribute it and/or modify
+%% it under the terms of the GNU General Public License as published by
+%% the Free Software Foundation; either version 2 of the License, or
+%% (at your option) any later version.
+%%
+%% This program is distributed in the hope that it will be useful,
+%% but WITHOUT ANY WARRANTY; without even the implied warranty of
+%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+%% GNU General Public License for more details.
+%%
+%% You should have received a copy of the GNU General Public License
+%% along with this program; If not, see <http://www.gnu.org/licenses/>.
+
+% Example program of the optimal interpolation toolbox
+
+
+% the grid onto which the observations are interpolated
+
+[xi,yi] = ndgrid(linspace(0,1,100));
+
+% background estimate or first guess
+xb = 10 + xi;
+
+% number of observations to interpolate
+
+on = 200;
+
+% create randomly located observations within 
+% the square [0 1] x [0 1]
+
+x = rand(1,on);
+y = rand(1,on);
+
+% the underlying function to interpolate
+
+yo = 10 + x + sin(6*x) .* cos(6*y);
+
+% the error variance of the observations divided by the error 
+% variance of the background field
+
+var = 0.1 * ones(on,1);
+
+% the correlation length in x and y direction
+
+lenx = 0.1;
+leny = 0.1;
+
+% number of influential observations
+
+m = 30;
+
+% subtract the first guess from the observations
+% (DON'T FORGET THIS - THIS IS VERY IMPORTANT)
+
+Hxb = interp2(xi(:,1),yi(1,:),xb',x,y);
+f = yo - Hxb;
+
+% run the optimal interpolation
+% fi is the interpolated field and vari is its error variance
+
+[fi,vari] = optiminterp2(x,y,f,var,lenx,leny,m,xi,yi);
+
+% Add the first guess back
+
+xa = fi + xb;
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