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Bjorn Gustavsson


Last seen: 1 day ago

UIT, the Arctic University of Norway

1,118 total contributions since 2001

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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...

20 hours 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...

1 day 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...

1 day ago | 0

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 ...

2 days 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...

2 days 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...

2 days 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 ...

4 days ago | 0

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

8 days ago | 0

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...

10 days 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 = ...

15 days ago | 0

Answered
Solving coupled ODEBVP using MATLAB
There's an old "proverb" going something like "when in danger when in doubt run around in circles scream and shoot". I vaguely ...

15 days ago | 0

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Answered
What MATLAB functions are underappreciated?
Just a couple of basic ones: lscov - linear regression when there is a data-covariance-matrix svd (to use together with Tikhon...

16 days ago | 0

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Getting two components for one frequency in FFT
The fft is a circular Fourier transform, there will always be some spectral leakage from frequencies that are not exactly period...

17 days ago | 1

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Answered
Local macro in STATA?
That is generally a poor programming pattern (read this as: "This is a really poor idea!"). You should aim to write your code su...

18 days ago | 0

Answered
function for addition 2^16 modulo
Just make sure that your ints a and b are in int32 or larger number of bit-formats, then use: C = mod(a+b,2^16) HTH

19 days ago | 1

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how do I classify image based on smoothness and high frequency?
For measure of smoothness I'd go with something like this: d2I = del2(I); % laplacian of your image (grayscale, double). From ...

19 days ago | 0

Answered
Horizontal First Differencer on a Matrix
Have a look on the help and documentation to diff. For this case use: y = diff(x,[],2); % or explicitly 1st difference: y = d...

20 days ago | 0

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Answered
How to remove space between subplots of heatmaps?
If you use the axes-handle output from subplot you can then set any of their properties as you desire: sph = subplot(3,1,1); %...

20 days ago | 0

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If a structure exists in a file
You can explicitly check for the existense of a variable in a .mat-file: qwe = whos('-file','your-filename.mat','cDA_External_S...

21 days ago | 0

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Answered
help debugging 3-D plot code
You have to get your equations for x, y and z right: x = a*cos(phi).*sin(theta); y = b*sin(phi).*sin(theta); z = b*cos(theta)...

21 days ago | 1

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Answered
Combined mean monthly values from 24 years of monthly data
Something like this perhaps: BV = table2array(baseline_values); clf subplot(2,1,1) imagesc(reshape(BV(:,4),12,[])') % Illust...

21 days ago | 0

Answered
Plotting negative values on an histogram
It seems likely that you've mixed up BinCounts and BinEdges - it doesn't make much sense to have a negative number of something ...

21 days ago | 0

Answered
M-point averaging filter to an image
Read the help and documentation for conv2. HTH

21 days ago | 0

Answered
Why doesn't the ode15s solver work when I switch 'k1q','k2q','k12q' from a single value into vectors(more values)?
When k1q is an array you will get an error when you try to assign the product of that array with the scalar C(1) to dCdt(1) whic...

22 days ago | 1

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Answered
i am getting error in line 18 of invalid use of operator.please help me solving this
OK, so you want to solve 3 coupled equations of motion for some harmonically varying solution. First you have to understand the ...

23 days ago | 0

Answered
make a better map
You should try: shading flat instead of the interp option. You will have to accept the fact that you only have data in a 32-by...

23 days ago | 0

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Answered
Solving differential equations to get accurate plot as shown.
Since you get an oscillatory behaviour of (primarily) Cecm and Crec it is very likely that you have a bug for some of the reacti...

23 days ago | 0

Answered
How to use chebop function?
Have you installed the chebfun package? Have you added the chebfun install directory to the matlab-path? If you have it install...

24 days ago | 0

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Answered
Improving speed of readtable
It is a rather large data-file to read. You might reduce the read-time if you use load instead of readtable - that should reduce...

24 days ago | 0

Answered
How to create and plot an oloid in MATLAB
Have a look at the help and documentation of the convhull function. That should give you a solution for this task - in the sense...

24 days ago | 0

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