Bjorn Gustavsson

UIT, the Arctic University of Norway

Last seen: 1 jour ago | Active since 2001

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Answered
Unexpected behavior of FFT
In the field (IS-radar) I work we have typical carrier-frequencies of 224-1000 MHz and the modulation band-width is a couple of ...

3 jours ago | 0

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HELP need to run Chebyshev code!
Save your chebeval-function in a separate file chebeval.m. Then call that function from your script. For now you can put both sc...

4 jours ago | 0

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SIR model with recovered individuals may lose their immunity and become reinfected with the disease. But came with a failure about integration tolerances
You have an error in the SIR-equations. They should look something like this: %% fc_ode_SIR function dq = fc_ode_SIR(~,q,p) % ...

6 jours ago | 0

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Skipping certain lines using fscanf
For this rather loose file-format specification that you've been given (meaning that in a couple of days, weeks or months it wil...

6 jours ago | 0

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PLOT surface using 3 vectors of same length (NEED HELP!!!)
You can use multiple indices in the variables you create. For example if you do things like this: b=0; for i = -200:1:200 ...

12 jours ago | 0

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Gradient Descent Implementation on a function, as opposed to an equation
You could do something like this: 1, rewrite the function to take an array as input-parameter instead of a number of scalar par...

18 jours ago | 0

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Y-values for the histogram
Perhaps you look for histcounts? Seems like that is the function that returns what is plotted in histogram. HTH

19 jours ago | 0

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How to fix "matrix dimensions must agree" error
Whe you run into problems like this you will have to learn to use the debug-capabilities of matla. Do this at the command-line: ...

19 jours ago | 0

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adding counts of ordered pairs
One way to go about this is to use sparse: A1 = [1 4 3; 3 5 1; 12 4 7; 13 5 2; 14 1 1]; A2 = [1 5 ...

19 jours ago | 0

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Answered
How to use Eigenvector and Eigenvalues of a matrix to formulate Entropy equation?
First you should extract the eigenvalues from the diagonal matrix (mainly for convenience): vLambda = diag(Vect); Then you wan...

20 jours ago | 0

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Answered
Simultaniously fitting 4 functions: two functions share all parameters, all four functions share one parameter
function errtot = four_errorfcns(pars1to5,Xall,Yall,sigmaYall) err1 = sum( ( f1(pars1to5(1:3),Xall(1,:))-Yall(1,:) ).^2/sigmaYa...

24 jours ago | 0

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How to create stacked quiver plots?
This sounds like a straight use of quiver3? Either h1=quiver3(slice2(:,1),... slice2(:,2),... slice2(:,...

24 jours ago | 1

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Answered
Plot multiple x axes on the bottom of a graph
You should have some good use of a couple of such tools from the file exchange: dual_axes addaxis multiple-y-axes The last t...

24 jours ago | 0

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Integration of system of ODEs fails, unable to meet integration tolerances
After only quickly looking at your problem, it seems to me that you launch the body in a direction into Earth. The first 2 and l...

24 jours ago | 1

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Answered
Unrealistic fitting confidence levels in noisy data
This is most likely due to the large number of data-points you have. Compare with the simpler case of the uncertainty of the ave...

24 jours ago | 1

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Using geointerp and los2
If you check the documentation (browse on from the help) you will see this: load topo Create a raster reference object assoc...

25 jours ago | 0

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M_map file with contourf
You might get away by modifying the colormap with the brighten function, perhaps something like: brighten(-0.5) This should ch...

26 jours ago | 0

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Answered
How to integrate using trapz function
The variable in X1 seems awfully constant, at 0.0166. The first input to trapz should be the x-coordinate of the points at which...

26 jours ago | 0

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Answered
How to convert gray image frame into video frames?
Have a look at the help and documentation for the VideoWriter and writeVideo functions. HTH

environ un mois ago | 0

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how to attach a matrix generated in loop below a matrix with same row size generated in previous iteration?
The "natural" interpretation of below to me would be something like this: C = [A;B]; But that only works if the number of colu...

environ un mois ago | 0

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How can i fit ODE parameters to given frequency and amplitude data pairs with "lsqcurvefit"?
There are two issues you will have to solve. The first is to convert your second order ODE to two coupled first-order ODEs. The ...

environ 2 mois ago | 0

Answered
Surface plot of scatter data X,Y,Z where unknown data is noise
If you have a good handle on the noise-distribution you could do that. But for plotting purposes I would go for setting missing ...

environ 2 mois ago | 1

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Test if input number is divisible by 3.
Have a look at the help and documentation for while. Also from the question I guess that you're reasonably new to programming. I...

environ 2 mois ago | 0

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Fast fourier tranformer for Time series data
It seems that you're a bit too close to the Nyquist frequency. If you try: [NUM,TXT,RAW]=xlsread('data.xlsx'); dt = mean(diff(...

environ 2 mois ago | 0

Answered
Anisotropic diffusion for a fingerprint image: resolution issues.
You might find that you have more control over the anisotropic diffusion with the cedif or eedif functions from the nonlinear-di...

environ 2 mois ago | 1

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Detect and remove outliers in signals
Be very cautious when changing bad-data-values to some default-value - that will eventually lead to (since we all know that the ...

environ 2 mois ago | 0

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Histogram or bar graph with greater than bin?
Maybe something like this would be good enough/a step on the way: a = 75*randn(2048,1).^2; h = histogram(min(a,260),0:10:260,'...

environ 2 mois ago | 1

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Answered
Append to original file name and and save new file to directory?
You should be able to separate the path, name and ext of the full filename using fileparts. That should make it reasonably strai...

environ 2 mois ago | 0

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Answered
Linear interpolation using inter1 function in matlab
First you should learn to read the help to the function you struggle with. Do that carefully and you will see that the typical u...

environ 2 mois ago | 0

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Is it possible to generate a sine wave like this? I tried combining 50hz, 100hz and 200hz together but I did not get something like this picture that I provided here.
Yes it is possible. You will have to make the phase-angle match at the frequency transitions (for simplicity make the time-windo...

environ 2 mois ago | 1

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