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# Bjorn Gustavsson

### UIT, the Arctic University of Norway

Last seen: Today Active since 2001

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Answered
Multiple curve fitting via optimization
For this type of problem I would use lsqnonlin, so read the help and documentation of that function and what additinoally you ne...

5 days ago | 2

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Answered
Why cant I get a stable Cranck Nicolson discretization?
(caveat: I didn't run your code or analyze it, but speak from my experience with CN) Most likely you take too long steps in time...

6 days ago | 0

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Passing a matrix between several callbacks
If you have all your user interface in one figure (some calculator-like programme), then one way to store the matrix is in the '...

7 days ago | 0

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Joint Probability Density estimation function
Search the excellent File Exchange for everything you need but cannot find in your matlab-installation! Here's what comes up wh...

8 days ago | 0

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Integrating a line integral e^x(sinydx + cosydy) over an ellipse 4(x+1)^2 + 9(y-3)^2 = 36
For the integration you should use Green's theorem. It is beautiful, especially for this case. For the vector-field-plot you ca...

8 days ago | 2

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How to calculate a double integral inside the domain of intersection of two functions?
Perhaps you can use Green's theorem (you'd be very lucky if you could - but if you were to be that lucky in this case it would b...

15 days ago | 0

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Create a function handle that is a sum of function handles
Your specification is a bit ambiguous to me, but if I interpret it such that you want to fit a function such that: (I've used...

19 days ago | 1

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How can I find the filter bandwidth of Savitzky-Golay filtering?
QD suggestion: x = randn(4096,1); x_sgf = sgolayfilt(x,order,framelength); fx = fftshift(fft(x)); fxsgf = fftshift(fft(x_sgf...

19 days ago | 0

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Further processing of contour plot data
I would not do the average of the contours in a region, because if you have a rather flat region with a single spike in some reg...

20 days ago | 1

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Check summation from n=0 to 5 |n><n| in MATLAB?
If |n><n| is the same as <n||n> then you should have a look at the help and documentation to dot. That function will not general...

21 days ago | 0

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Decimal indexing for arrays in MATLAB
Have a look at the help and documentation for griddedInterpolant. That function might be what you're looking for. It creates a f...

22 days ago | 1

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How can I plot 18 lines in different colors on a single plot?
For that type of tasks I have had good use of the cmlines-function in the colormap-and-colorbar-utilities toolbox on the file ex...

22 days ago | 0

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How to adjust a curve fit such that it goes through a specific point
If this is a plot of an electron-density profile observed with an IS-radar, then your ionosonde fOF2 point is (expected to be) a...

22 days ago | 0

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i have a loop which runs from 1 to 7 producing four different figures per run. How do i automatically save each of these figures inside the loop. The loop is given below.
One thing I regularly do is something like this: fig_basename = 'My_current_fig'; for i1 = 1:7 %plot-and-decorate-code f...

23 days ago | 0

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Answered
How to rearrange random binary input for each iteration?
Have a look at the nextperm tool on the file exchange. It will allow you to cycle through all permutations. HTH

23 days ago | 0

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Combine different size matrix
If your D is a scalar that you want to expand into a diagonal matrix then perhaps you can do something along these lines: szA =...

23 days ago | 0

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How to detect wide ball in cricket using MATLAB. What should be the simple code for it.
One thing you can (should) try is to look at the differences between frames, that is subtract the previous frame from the curren...

28 days ago | 1

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How to extract data from specific row
You can do things like this in matlab: data_oi = data(data(:,1)==1|data(:,1)==2,:); This wouild give you your data of interest...

29 days ago | 0

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Answered
issue with colormap (colorcube)
Check that/if/how the two m-files differ. If they differ, copy the one you like better to the other system into a directory you ...

1 month ago | 0

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Why am I obtaining incorrect values for Lipschitz 1/2 norms using the central difference method?
You've forgot to take the derivative of the function on-line, and you seem to take some kind of derivative on your own computer....

1 month ago | 0

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How can write Dirac bra-ket notation in MATLAB? Example please.
That depends on what you want to apply the bra-ket on. If it is simple vectors you might get away with simple inner-products usi...

1 month ago | 1

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Answered
strange error with varfun and anonymous function
These 2 modifications work: tbl = table(randn(5,1)); func = @(x) cumsum(x); varfun(func, tbl) % ans = % 5x1 table % F...

1 month ago | 0

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Answered
How to solve system of ODEs with unknown initial value?
This works: % one second-order ODE rephrased as 2 coupled first-order syms q0 [2 1] syms a1 a2 syms q(t) [2 1]; A = [...

1 month ago | 0

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Get grayscale like image from 2D representation of 3D random plot
Have a look at the help and documentation of histcounts2. That function will allow you to calculate this type of cumulative coun...

2 months ago | 1

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Answered
Standard Deviation of an histogram
You don't want the standard deviation of the histogram. You want the standard deviation of the pixel intensities in the image. Y...

2 months ago | 0

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Differential Equations with Inputs (Tank Draining Problem)
What you should do is to make a small modification of your ODE-function - such that it takes an additional input argument where ...

2 months ago | 0

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Answered
Shift a square matrix along a bigger square matrix by one
Have a look at the help and documentation for the function circshift. That function should solve the problem you have described....

2 months ago | 0

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Who owns the copyright of the code?
This will surely differ from country to country. Ask your trade union. In Sweden it is (at least used to be) so that if the com...

2 months ago | 1

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Answered
How to access the double cell 5*1 ?
You could use cell2mat to convert the 5x1 cell-array with elements n_j x 3 into a matrix with n_many x 3 and then proceed as per...

2 months ago | 0

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How to find the count of vertical lines in an image using Fourier Transform in MATLAB?
Why in the world do you want to use the Fourier transform to do that? You might be OK-ish for this specific pattern since it (su...

2 months ago | 1