Rank: 1156 based on 100 downloads (last 30 days) and 7 files submitted
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Michael Völker

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Professional Interests:
signal processing in MRI

 

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01 Oct 2013 Screenshot simulate motion in Cartesian MRI Simulates Point Spread Function (PSF) and k-space data for motion in Cartesian sequences. Author: Michael Völker mri, imaging 15 0
19 Dec 2012 Screenshot MRI Partial Fourier reconstruction with POCS Fast and robust reconstruction of Cartesian partial Fourier MRI data with POCS Author: Michael Völker partial fourier, pocs, mri, asymmetric echo, reconstruction, fft 34 0
31 Oct 2012 Screenshot hypersphere / n-sphere Generate n-dimensional Ellipsoid or Sphere Author: Michael Völker hypersphere, nsphere, spheren, disc, circle, sphere 14 2
  • 5.0
5.0 | 2 ratings
06 Sep 2012 Execute default function of a MATLAB installation Execute the default function available as an m-file in MATLAB's installation directory. Author: Michael Völker shadowed files, overloading, function precedence, which, builtin 9 2
02 Aug 2012 man page command like in Unix/Linux A trivial wrapper function to Matlab's doc command. Author: Michael Völker man, doc, reference, help, rtfm, manual 10 0
Comments and Ratings by Michael View all
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05 Mar 2014 Fast 3D/2D Region Growing (MEX) A very fast 2D and 3D region growing algorithm implemented in c++. Author: Christian Wuerslin

This is well done!

I have a minor suggestion for the visualization of the result (nargout == 0). For large No. of slices in a 3D data set, the output of montage() is very hard to grasp. My suggestion is to present only image slices that are part of the segmented volume:

Below line 89, add
% reduce montage size by selecting the interesting slices, only
slices = squeeze( sum(sum( dMask(:,:,1,:) ,1),2) > 0 );

And change line 90 to:
figure, montage(dImg(:,:,:,slices));

04 Mar 2013 disperse Assign elements of an input array to individual output variables with a single function call. Author: Sam Hallman

Very nice, simplistic code.

However, if the input is a complex column vector, you accidentally conjugate it, due to this line:
x = x';

Could you please repair that?
--> x = x.';

24 Jan 2013 hypersphere / n-sphere Generate n-dimensional Ellipsoid or Sphere Author: Michael Völker

Hi gang,

I actually need that for masking 2D data, only. Or to help me out in some quick simulations.
But since I only used simple Pythagoras, I thought I'd make it more flexible with n-dimensional support.

And yes, I am really not surprised that you can use it for a 3D ROI. :-)

22 Jan 2013 MTIMESX - Fast Matrix Multiply with Multi-Dimensional Support Beats MATLAB 300% - 400% in some cases ... really! Author: James Tursa

Charles,

for my own record and to make it machine-searchable, I wrote earlier how I was able to compile mtimesx. Taking the liberties to quote myself:

> On a 64Bit Debian based Linux I managed to compile it with
> mex -DDEFINEUNIX CFLAGS="\$CFLAGS -march=native" -largeArrayDims -lmwblas -lmwlapack -lgomp mtimesx.c
> using gcc-4.5.

Can you try that, or did you already try?

Michael

13 Dec 2012 My attempt to write the Hungarian Algorithm WARNING: It's not completely functional. This was just a "simple" school project. Author: ACLNM

If you know it does not yet work as intended and you give no (english) comment on what it does and how to use it, why do you upload it? Who should benefit from it?

Comments and Ratings on Michael's Files View all
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19 Feb 2013 hypersphere / n-sphere Generate n-dimensional Ellipsoid or Sphere Author: Michael Völker JakobK

24 Jan 2013 hypersphere / n-sphere Generate n-dimensional Ellipsoid or Sphere Author: Michael Völker Völker, Michael

Hi gang,

I actually need that for masking 2D data, only. Or to help me out in some quick simulations.
But since I only used simple Pythagoras, I thought I'd make it more flexible with n-dimensional support.

And yes, I am really not surprised that you can use it for a 3D ROI. :-)

24 Jan 2013 hypersphere / n-sphere Generate n-dimensional Ellipsoid or Sphere Author: Michael Völker gang

hello Michael, thanks for your code,do you try this for getting the 3D shpere ROI of volume?
I just get the problem,thank you!

06 Sep 2012 Execute default function of a MATLAB installation Execute the default function available as an m-file in MATLAB's installation directory. Author: Michael Völker Völker, Michael

Jan Simon,

> I will definitely avoid to overload built-in functions

the same is (usually) true for me.

But the unbelievable 64-step-colormap-issue in current MATLAB *is* in fact a reason to change MATLAB's behaviour for all platforms where size(colormap) == 64.

At the moment, I see no other usecase for myself, but in these pretty rare cases, it is nice to have the possibility to patch MATLAB...

06 Sep 2012 Execute default function of a MATLAB installation Execute the default function available as an m-file in MATLAB's installation directory. Author: Michael Völker Simon, Jan

I will definitely avoid to overload built-in functions, because this can interfere with foreign code.
Some toolbox functions have been changed from M-file to built-in in the past, such that code relying on a function to be the one or the other type, will be platform dependent.

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