Rank: 551 based on 191 downloads (last 30 days) and 13 files submitted
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Stephan Koehler

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WPI
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30 Jun 2014 dir_crawler.m crawls through a directory tree and returns sub-directories and files with ability to search by name Author: Stephan Koehler directories, search, files 8 0
09 Aug 2013 Screenshot running average and standard deviation of vectors computes the running average and standard deviation of vectors or matrices for a given window size. Author: Stephan Koehler mean, standard deviation, running average 26 1
06 Aug 2013 TA_txt2MAT converts text datafile from TA rheometer to a .mat datafile. Author: Stephan Koehler data conversion, rheology, ta instruments 9 0
17 Jun 2013 Screenshot Error Propagation Numerically calculates uncertainties of a function using random numbers to simulate function inputs Author: Stephan Koehler error analysis, error propagation 21 0
  • 5.0
5.0 | 1 rating
19 Apr 2013 Screenshot binning a point cloud, 3D scattered data, in the X-Y plane Take a set of XYZ points, and returns average Z values for corresponding bins in X & Y planes. Author: Stephan Koehler image processing, signal processing, statistics 15 1
Comments and Ratings by Stephan View all
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20 Mar 2014 CONV2 Overlap-add Method Overlap-add method of CONV2 using FFT2. Author: Luigi Rosa

Incredibly fast. I use conv2 a lot, and replacing with conv2olam makes calculations much, much faster.

Here is a snippet of code to return the same output as conv2(a, b, 'valid' ):

out = conv2olam( a, b );
out = cnv_cone2( floor(length(b)/2)+[1:size(a,1)], floor(length(b)/2) + [1:size(a,2)] );

13 Mar 2014 save2pdf Saves a figure as a PDF as it appears on the screen. Author: Gabe Hoffmann

05 May 2012 Generalized Nonlinear Non-analytic Chi-Square Fitting Performs chi-square fit with uncertainty estimation when measurement errors are known. Author: Nathaniel Brahms

Question: Could you also provide 90% confidence intervals for the fitting parameters, instead of just the 68%?

05 May 2012 Generalized Nonlinear Non-analytic Chi-Square Fitting Performs chi-square fit with uncertainty estimation when measurement errors are known. Author: Nathaniel Brahms

20 Aug 2011 Linear Regression with Errors in X and Y Calculates slope and intercept for linear regression of data with errors in X and Y. Author: Travis Wiens

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23 Apr 2014 running average and standard deviation of vectors computes the running average and standard deviation of vectors or matrices for a given window size. Author: Stephan Koehler Giovanni

I Have a suggestion to the code. It fixes only code for 1d vectors. Using std=sqrt(avg(X^2)-(avg(x))^2)) it is possible to reduce the amount of points discarded at the edges to half the window length.

Suggested code:

if size( data, 2) == 1
target = ones(filter_width, 1)/filter_width;
running_avg = conv2( data, target, 'same' );
running_std = sqrt( conv2( (data).^2, target, 'same' )-running_avg.^2 );
% cropping invalid region
running_avg([1:filter_width/2, end-filter_width/2+1:end]) = nan;
running_std([1:filter_width/2, end-filter_width/2+1:end]) = nan;

20 Apr 2013 binning a point cloud, 3D scattered data, in the X-Y plane Take a set of XYZ points, and returns average Z values for corresponding bins in X & Y planes. Author: Stephan Koehler yagnesh

is it usefull for 3D face recognition?

09 Oct 2012 Error Propagation Numerically calculates uncertainties of a function using random numbers to simulate function inputs Author: Stephan Koehler Kresten

24 Nov 2009 new_dir.m This is an enhancement to MATLAB's dir function, for dealing with sequentially numbered files. Author: Stephan Koehler Simon, Jan

Bugs are fixed, descriptive warning on Windows for the -find flag, updated description on the FEX page (removed "Matlab 5.3"), considering directories, some improvements in the help section. No comments in the source. Useful and usable.

18 Nov 2009 new_dir.m This is an enhancement to MATLAB's dir function, for dealing with sequentially numbered files. Author: Stephan Koehler Simon, Jan

The function starts with overwriting VARARGIN - please remove this!
The help section now mentions, that the -find option works on Unix only. But a check in the function (if ~isunix, error('-find works on Unix only'); end) would be useful.
Please update the file information on the FEX: This function does still not run under Matlab 5.3.
The help section is still hard to read (for me) due to the formatting. A H1-line would be helpful (see LOOKFOR command).
Some simplifications are possible, e.g.: "numel({d.name})" equals "numel(d)",
"to_do = strncmp( varargin, '-', 1 );
neg_queery = ~to_do&strncmp(varargin, '~', 1 );" is easier as: "neg_queery = strncmp(varargin, '~', 1);".
Comments in the source are recommended generally.
I really like the idea of expanding DIR with a filter for numerical indices.

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