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Bjorn Gustavsson


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UIT, the Arctic University of Norway

1.138 total contributions since 2001

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Answered
How to difine the frequency range with the function 'nufft'?
To understand what you get out of a non-uniform Fourier-transform I find it educational to calculate the dftmtx and then purge t...

etwa 13 Stunden ago | 0

Answered
Consider preallocating for speed
In your code you change the values and type of Werte 4 times. That seems a bit excessive. I'd try something like this: 1 while ...

ein Tag ago | 0

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Answered
Coordinate Interpolation between mutiple points
To me it sounds like you in principle want to interpolate both your coordinates with respect to time between your hourly samples...

ein Tag ago | 0

Answered
Conversion of space-time data to wavenumeber-time data
Provided that your data is sampled on a regular spatial grid it should be as simple as to perform a (perhaps windowed) fft in th...

ein Tag ago | 0

Answered
I have recorded a rgb video and extract g frames vector and calculate it's mean now I want to calculate beats per minute kindly help how can I calculate BPM
In order to estimate frequencies you have to look at the time-variation of your signal, depending on the variability of this you...

5 Tage ago | 0

Answered
How to calculate image resolution (full-width-at-half-maximum) of a point source?
I'd start with some simple models for your image response (2-D Gaussian, sinc^2(x).*sinc(y)^2) and fitted the parameters of thos...

9 Tage ago | 1

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Answered
generate random integer number with a specific mean
Have a look at the help and documentation of randi and then try and test some things. Finally have a deep think about what your ...

12 Tage ago | 0

Answered
How can I save subplot figures together?
Wouldn't this do: print('-depsc2','-painters','Your2subplotfig.eps')

12 Tage ago | 0

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Answered
Event Detecting in Event-based ODE
In order to advice the contents of the event-function is necessary. The only thing to point out is that the ode-solvers use nume...

12 Tage ago | 0

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Answered
Detecting phase difference between two channels
Does something like this extract variations that are related to the breathing-pattern: phi_u = unwrap(atan2(raw_ad_data_sine,ra...

13 Tage ago | 0

Answered
IGRF model Implementation (Calculating the Partial Derivatives of the Legendre Polynomials)
Have a look at the IGRF implementations available on the file exchange: international-geomagnetic-reference-field-igrf-model, in...

16 Tage ago | 0

Answered
Solving an integral equation
For this I think pen-and-paper might be easier than using the symbolic toolbox. Simply differentiate both sides of your definiti...

20 Tage ago | 1

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Answered
save filename by values using a variable
Ok, that should be possible. Someting like this: % First lets get you the date-string-component in your desired format (guessin...

20 Tage ago | 1

Answered
How can I rotate a vector by a certain amount along a specific plane?
Simply take another vector that lies in your plane, here c (you should understand why we can use c straight away). Then form an ...

23 Tage ago | 1

Answered
I want my legend just like the pic. 2 variables in 2 columns at the same legend
Solve the problem at the root: legendString = "N = " + string(N) + ", M = " + string(M); ph = plot(x,N.*x'); % Better controll...

28 Tage ago | 0

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Answered
stack multiple 2D images
Unfortunately matlab is a bit weak when it comes to displaying volumetric data. You can use the slice function and use the alpha...

etwa ein Monat ago | 0

Answered
Poor resolution on EPS caused by fill function
As far as I understand post-script does not really support transparency. Therefore when writing figures with transparent objects...

etwa ein Monat ago | 0

Answered
All possible combination based on 2^n
You could use dec2bin: allpossibles = dec2bin(0:(2^n-1)); You'll have to extract the indices from the columns but that should...

etwa ein Monat ago | 0

Answered
ODE for the modelling of polymers degradation - products of sums, additional matrix in the function?
It seems to me that you might have your problems when calculating the products of the radicals. Your ODE-function for the couple...

etwa ein Monat ago | 0

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Answered
How to plot actual amplitude on the colorbar using STFT (spectrogram)
If you read the help for spectrogram you'll find this: [...] = spectrogram(...,SPECTRUMTYPE) uses the window scaling ...

etwa ein Monat ago | 1

| accepted

Answered
Flood map using Mapping toolbox
Well there are a couple of resources you can use. Steve Eddins (sp?) wrote a series of posts on upslope-area, and another on det...

etwa 2 Monate ago | 0

Answered
How does pcolor basically work? Please help me understanding pcolor, color matrix, and colormap work.
If you add a call: colorbar to your tests you will see what levels of C corresponds to what colours in the colormap. That will...

etwa 2 Monate ago | 0

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Answered
nonlinear fit with function a*exp((q1+i*q2)*x)/sqrt(x)
This seems like you need to take a standard step from the physicsist's complex representation (which admittedly we often use a b...

etwa 2 Monate ago | 0

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Answered
[Image Restoration, Wiener Filter] Ifft2 gives NaN complex matrix
Just to get up to speed: that then is F-transformed to: which we can "solve" as: or after multiplying the RHS with the ...

etwa 2 Monate ago | 1

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Answered
Keeping values of function when solving ODE
As your ODE is written above we have to ask: Why bother? y is deterministically given provided your input parameters and the tim...

etwa 2 Monate ago | 1

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Answered
Deconvolution of a combination of Gaussians signal
If you have a signal that is smeared or convolved with some point-spread-function you can to some extent undo that by using eith...

etwa 2 Monate ago | 0

Answered
How to solve the second-oder differential equations with two variables using ODE45 or whatever
To the best of my "reading-ability" you seem to have it right in ODE-defining function. From your equations I expect them to be ...

etwa 2 Monate ago | 0

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Answered
Best guess/optimization solution needed
From the information you've given this sounds like a "reasonably" straightforward optimization-problem. You could try something ...

etwa 2 Monate ago | 0

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Answered
How to solve differential equations involving matrices?
Based off of your description I see no difference betwee solving these 4 x 4 coupled ODEs and solving them as 16 x 1 coupled ODE...

etwa 2 Monate ago | 0

Answered
Remove temporal intensity changes in image series
I'd try something like this: ImFiles = dir('*.png'); % well you have your images somehow... roi_c = [11 37 17 51]; for iIm = ...

2 Monate ago | 0

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