Rank: 140 based on 348 downloads (last 30 days) and 14 files submitted
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Wolfgang Schwanghart

E-mail
Company/University
University of Basel
Lat/Long
47.56169891357422, 7.58060884475708

Personal Profile:
Professional Interests:
GIS, Physical Geography, Hydrology

 

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Files Posted by Wolfgang View all
Updated   File Tags Downloads
(last 30 days)
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24 Nov 2011 Screenshot Experimental (Semi-) Variogram calculate the isotropic and anisotropic experimental (semi-) variogram Author: Wolfgang Schwanghart kriging, variogram, spatial modelling, dimensions, geostatistics 87 14
  • 4.85714
4.9 | 7 ratings
14 Oct 2010 Screenshot Ordinary Kriging 2D-interpolation using geostatistics Author: Wolfgang Schwanghart kriging, geostatistics, variogram 79 0
  • 3.5
3.5 | 2 ratings
14 Oct 2010 Screenshot variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart kriging, variogram, spatial statistics, ipdm, optimization, geostatistics 76 9
  • 5.0
5.0 | 4 ratings
13 Jul 2010 Screenshot Line Simplification Recursive Douglas-Peucker Polyline Simplification (Iterative Endpoint Fit) Author: Wolfgang Schwanghart approximations, interpolation, polyline, vertex reduction, mathematics, approximation 47 7
  • 5.0
5.0 | 3 ratings
21 Sep 2009 Screenshot cropmat crop arrays with axis-aligned minimum bounding box Author: Wolfgang Schwanghart matrix manipulation, matrix, image processing 8 0
Comments and Ratings by Wolfgang View all
Updated File Comments Rating
18 Jan 2012 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart

Hi Aditi,

yes, this is possible, but you have to make some changes to the function.

Note that the general variogram parameters are in vector b.

% b(1) range
% b(2) sill
% b(3) nugget

So let's say you fit your horizontal data such that
b(1) = 1;
b(2) = 5;
b(3) = []; % no nugget

Then, before fitting your next model, edit to the following lines (302-313)

% generate upper and lower bounds when fminsearchbnd is used
switch lower(params.solver)
    case {'fminsearchbnd'};
        % lower bounds
        % lb = zeros(size(b0));
        lb = [0 5];
        % upper bounds
        if nugget;
            ub = [inf max(gammaexp) max(gammaexp)]; %
        else
            % ub = [inf max(gammaexp)];
            ub = [inf 5];
        end
end

This should work. Make the obvious changes if you employ a nugget variance.

Is this a common problem and should it be implemented in variogramfit? If yes, let me know.

Best regards,
Wolfgang

18 Jan 2012 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart

Hi Adam, right!

  d.val = gammaexp
  d.dist = h

I know it's a little pedestrian...

Regards, Wolfgang

28 Nov 2011 Experimental (Semi-) Variogram calculate the isotropic and anisotropic experimental (semi-) variogram Author: Wolfgang Schwanghart

Hi Jorge,

are those data gridded? If yes, you should call the function like this:

d = variogram([x(:) y(:)], impedance(:), 'nrbins',50,'anisotropy',true,'thetastep',30);

Best regards,
Wolfgang

24 Nov 2011 Experimental (Semi-) Variogram calculate the isotropic and anisotropic experimental (semi-) variogram Author: Wolfgang Schwanghart

Hi Jorge. I have just uploaded a new version with a bug removed. Please take this one as soon as it is available (probably by 25 Nov 2011). Then, in order to obtain variograms for different directions, just calculate the anisotropic variogram. E.g. for obtaining variograms in 0 and 90° direction, you can do following:

d = variogram([x y],z,...
'nrbins',50,'anisotropy',true,...
'thetastep',30);

plot(d.distance,...
d.val(:,find(d.theta==0 | d.theta==pi/2)));

You may choose tighter angular bins. In this case it will be 0+-15 and 90+-15.

HTH, Wolfgang

10 Sep 2011 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart

@ James,

I think that this should be feasible without too much effort. I would, however, not want to implement it in the existing variogramfit function, but write a wrapper, that evaluates the function for various models and selects the one that has the highest coefficient of determination.

Comments and Ratings on Wolfgang's Files View all
Updated File Comment by Comments Rating
18 Jan 2012 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart Schwanghart, Wolfgang

Hi Aditi,

yes, this is possible, but you have to make some changes to the function.

Note that the general variogram parameters are in vector b.

% b(1) range
% b(2) sill
% b(3) nugget

So let's say you fit your horizontal data such that
b(1) = 1;
b(2) = 5;
b(3) = []; % no nugget

Then, before fitting your next model, edit to the following lines (302-313)

% generate upper and lower bounds when fminsearchbnd is used
switch lower(params.solver)
    case {'fminsearchbnd'};
        % lower bounds
        % lb = zeros(size(b0));
        lb = [0 5];
        % upper bounds
        if nugget;
            ub = [inf max(gammaexp) max(gammaexp)]; %
        else
            % ub = [inf max(gammaexp)];
            ub = [inf 5];
        end
end

This should work. Make the obvious changes if you employ a nugget variance.

Is this a common problem and should it be implemented in variogramfit? If yes, let me know.

Best regards,
Wolfgang

18 Jan 2012 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart Aditi

Can I use this to simultaneously fit two variograms using some of the same parameter values? E.g., I want to fit both the horizontal and vertical data such that they have the same sample variance parameter.

18 Jan 2012 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart Schwanghart, Wolfgang

Hi Adam, right!

  d.val = gammaexp
  d.dist = h

I know it's a little pedestrian...

Regards, Wolfgang

18 Jan 2012 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart Adam

question not function,excuse me :)

18 Jan 2012 variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart Adam

Please one stupid function,if I am doing right.
For this function I use output from function variogram d(val)=gammaexp and d(dist)=h?
Thank you a lot for those two functions!

Top Tags Applied by Wolfgang
geomorphology, geostatistics, hydrology, image processing, matrix manipulation
Files Tagged by Wolfgang View all
Updated   File Tags Downloads
(last 30 days)
Comments Rating
24 Nov 2011 Screenshot Experimental (Semi-) Variogram calculate the isotropic and anisotropic experimental (semi-) variogram Author: Wolfgang Schwanghart kriging, variogram, spatial modelling, dimensions, geostatistics 87 14
  • 4.85714
4.9 | 7 ratings
23 Nov 2011 Screenshot Robust spline smoothing for 1-D to N-D data SMOOTHN allows automatized and robust smoothing in one and higher dimensions w/wo missing values Author: Damien Garcia image processing, signal processing, statistics, smooth 84 11
  • 4.63636
4.6 | 11 ratings
14 Oct 2010 Screenshot Ordinary Kriging 2D-interpolation using geostatistics Author: Wolfgang Schwanghart kriging, geostatistics, variogram 79 0
  • 3.5
3.5 | 2 ratings
14 Oct 2010 Screenshot variogramfit fits different theoretical variograms to an experimental variogram Author: Wolfgang Schwanghart kriging, variogram, spatial statistics, ipdm, optimization, geostatistics 76 9
  • 5.0
5.0 | 4 ratings
13 Jul 2010 Screenshot Line Simplification Recursive Douglas-Peucker Polyline Simplification (Iterative Endpoint Fit) Author: Wolfgang Schwanghart approximations, interpolation, polyline, vertex reduction, mathematics, approximation 47 7
  • 5.0
5.0 | 3 ratings

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