Bjorn Gustavsson

UIT, the Arctic University of Norway

Last seen: Today | Active since 2001

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Curve Fitting in MATLAB
For this type of problems I learnt (before the arrival of the gui-curve-fitting tools) to use the standard function-minimization...

7 hours ago | 0

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2D FFT of a 4D matrix
Shouldn't this effectively be the same as running an FFT on the entire 4D-array (with some confusion about normalization-factors...

1 day ago | 0

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Losing pixels with imrotate
This happens due to aliasing-effects the discrete pixel-squares will start to mix and spread out between some neighboring pixels...

1 day ago | 0

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I have an array of 6,76,000 as txt file, how can I convert that into 52x13x1000.
You could try reshape, see the help and documentation of that function. If you dont get the elements in the right order with som...

4 days ago | 0

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Creating a gif file out of an animation
I had a great experience using gif from the file exchange to convert a series of plots into a gif-animation. Simple to use does ...

7 days ago | 0

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How can i form a filename from MATLAB identifier and correcting sntax error in "3dinvert.m"
There are restrictions of the filenames for matlab-functions, and as far as I recall it is supposed to not start with a number (...

7 days ago | 0

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does convex hull intersect?
You should have two file-exchange packages that solves your problem: fast-and-robust-curve-intersections curve-intersections ...

9 days ago | 0

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How to make a line plot with a colorbar as the third variable?
When I want to plot colour-coded curves I use one of these functions from the file exchange: cline, cline-m or plot-3d-color-li...

9 days ago | 0

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Polar Plotting of Data
The pcolor in polar coordinates is the polar version of pcolor. For those functions you will need some kind of 2-D surface-like ...

9 days ago | 0

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how to apply stft to audio signal?
You might do this, but the call to seconds looks spooky. From audioread you get the sampling-frequency fs, that is the sampling-...

9 days ago | 0

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Assign a value to each page of a 3D Matrix
If we stick to the first rule of programming (KISS) this should get the job done: A = zeros([3,4,5]); x = [10 20 30 2^.5 exp(1...

11 days ago | 0

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Find and visualize the divergence of a vector function F = yzi xzj xyk. Please help me guys, please
Simply use the divergence function. Read the help and documentation to that one. If you have analytical expressions and access t...

11 days ago | 0

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Solving eigenvalue problem with solve_bvp
In the mat4ode function the variable Ra is undefined. How would matlab know what value to give it? What dimension should it have...

11 days ago | 0

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how to denoising rgb image?
Well nothing but a simple goof. You simply swapped the green and blue channels in this line: restored_image = cat(3, out_redCha...

11 days ago | 0

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contour3-With 3 dimensions input arguments
Maybe you get what you need with the slice function, or perhaps isosurface. From my naive understanding we can draw iso-contours...

11 days ago | 0

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How to generate a rhythm that is based on an algorithm in matlab?
1, You search for some description of the algorithm that allows you to implement it. For example 5 minutes on googles first page...

12 days ago | 0

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How to deblur an image in frequency domain?
Most likely you have a problem with division-by-zero in the: Inv = Conv./avgFilter_fft; step. If you try to set those componen...

15 days ago | 1

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Find Angle using point coordinates?
You could use the general formulas for angle between vectors found here: angle-between-two-vectors-in-3d, which is a good answer...

15 days ago | 1

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How to randomly propagate 100 random targets with random headings (uniformly sampled over [0, 2π])
Yes. The image is constructed with pixel-resolution, that is kind of the definition of a pixel-based image sensor. You model the...

15 days ago | 0

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How can I extend polyfit line on loglog scale ?
When you calculate yhat you only do that for the first and last element of your x-values that you use for the fit. You should tr...

15 days ago | 0

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Matlab 2020b "Invalid text character. Check for unsupported symbol, invisible character, or pasting of non-ASCII characters."
It might well be that the "ˆ" symbol have been encoded to some othe character than "^" (I'm completely un-interested in characte...

1 month ago | 1

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Is there a way to compress non-integer data without loss using the CFITSIO library?
If you have data in double (32 or 64 bit-format), and want to keep it that way, dont' cook up your own casting-trickery - set th...

1 month ago | 0

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the diﬀerential equations by ode45
Start with the matlab on-ramp material. To find that search for "onramp" on the web-site. After doing that you should be able to...

1 month ago | 0

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Spectrogram: HOW TO CONTROL ZERO-PADDING for individual fft's of an ULTRA LONG sequence
Yes, in principle, zero-padding is used by spectrogram if nFFT is larger than the window-length. HTH

1 month ago | 0

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Calculus limits with MATLAB
Well get to it. If you are very new to matlab then have a look at On-ramp material - which should have you up and running faster...

1 month ago | 0

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Remove edges from concave triangulation
You problem is dificult in principle. How are the unwanted triangles supposed to be determined? In a general enough case that yo...

1 month ago | 0

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Plot spectra and spectrogram of acceleration data
Provided that your data actually spans 5 minutes your sampling-frequency is not 48 kHz, but rather 800 Hz. That changes the outp...

1 month ago | 0

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Which optimizer to use for SIR Epidemic Model?
One recommendation that you're not likely to like: The constant transition-probability of recovering/dieing has to be unbiologic...

1 month ago | 1

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to use tiledlayout to arrange pre-existing axes ?
When I need control of the figure layout and design I always save away the handles to "everything" - which makes it at least som...

1 month ago | 0

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How do i transform this equation system in to three dimensions?
Since this looks like the equations of motion for a solid body falling in a constant gravitational field with some velocity-depe...

1 month ago | 0