Rank: 1009 based on 145 downloads (last 30 days) and 13 files submitted
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Stephan Koehler

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Files Posted by Stephan Koehler View all
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(last 30 days)
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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 11 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 12 1
06 Aug 2013 TA_txt2MAT converts text datafile from TA rheometer to a .mat datafile. Author: Stephan Koehler data conversion, rheology, ta instruments 10 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 22 2
  • 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 13 1
Comments and Ratings by Stephan Koehler 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

Comments and Ratings on Stephan Koehler's Files View all
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15 Oct 2014 Error Propagation Numerically calculates uncertainties of a function using random numbers to simulate function inputs Author: Stephan Koehler Vali

Sorry for spamming, but if I do this:

func = @(x1,x2) x1.*x2;
[~, sig_f] =error_propagation( func, 1,1,0.5,0.5, 'hist')

I get sig_f = 0.7513, but it should be sqrt(0.5), am I doing something wrong?

15 Oct 2014 Error Propagation Numerically calculates uncertainties of a function using random numbers to simulate function inputs Author: Stephan Koehler Vali

Why is it that if I run this function with the same parameters it gives me slightly different values, each time I run it?
Otherwise great function!

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

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