Bjorn Gustavsson

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UIT, the Arctic University of Norway

953 total contributions since 2001

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Answered
4d smooth plot with slices
I suggest you use the slice function for that, this type of plots is what that function was designed for. If your Data are not...

9 hours ago | 0

Answered
how to solve this coupled ODE problem using ode solvers ?
If you want to use the odeNN functions you need to rewrite your 2 2nd-order ODEs into 4 1st-order ODEs, something like this: fu...

17 hours ago | 0

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How can I remove the additive periodical noise from the image?
Your Filterimage is not the notch-filter you need, that is only the 1-D amplitude (possibly power) of the 1-D fft of the filter ...

1 day ago | 0

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How to convert 'DDMMYYYYhhmm' into 'DD-MM-YYYY hh:mm'
You can do something like this to convert a date-string to another date-string: datestr(datenum(char(['190120211029';'140219671...

1 day ago | 0

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How does the time step affect the results of ODE solvers?
The way you call ode15s you simply chop up the time-intervall into sub-intervalls and integrate sub-intervall by sub-intervall. ...

2 days ago | 1

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running MATLAB ode45 back-to-back
Well if you have a problem like this (improvising for simplicity) ode1 = @(t,y,alpha) alpha*y; % exponential growth t_span1 = ...

2 days ago | 1

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Why does not coefficients vector include zero?
When I change the polynomial to: cf = fliplr(coeffs(x*3 + 2*z, [x y z],'All')) I get a 3-D array for the coefficients, as expe...

3 days ago | 0

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Using the cpsd function
Simply use the spectrogram function to calculate the spectrograms of your two time-series, something like this: [S1,F1,T1] = sp...

6 days ago | 0

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3d Plot “pile up 100 2d images” in 3d plane
You can use the function slice (see the help and documentation for details), but to do that you'll have to use 3-D arrays as inp...

9 days ago | 0

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Probability density function calculation from data
Step 1, combine the daily rain-data to a 20-by-365 matrix: for iY = 20:-1:1 rain_20years(iY,:) = rain_daily{iY}; % You'll ...

9 days ago | 0

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data fitting by Integration with variable limit with a unknown parameter.
You can do something like this: y_fcn = @(CT,x) CT(1) * 74.826 * (x./CT(4)).^3 * integral(t.^4.*exp(t)./(exp(t)-1).^2), 0, CT(4...

9 days ago | 0

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video camera data processing
Simplest way might be to use VideoReader: vidObj = VideoReader('Your-video.mp4'); Frame1 = read(vidObj,1); idx1toExtract = ...

9 days ago | 0

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Solving a system of ODE with Crank Nicholson
Note that you have a set of coupled ODEs not PDEs. The Crank-Nicholson method is developed for solving PDEs where we have both "...

13 days ago | 1

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How to create 3D array out of multiple 2D arrays of different dimensions?
Something like this ought to work: M2Dall = {m1,m2,m3,mN}; % Puting all matrices into one cell-array. for i3 = numel(M2Dall):-...

13 days ago | 0

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Pr4oblem with an ODE 45 " not enough input arguments"
Your definition of the ODEs is unconventional. I've always used to define coupled ODEs such that the dependent variables are in ...

14 days ago | 0

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How to plot contourf using following information?
You would have to make one contour-plot for each time-step: i_time = 1; contourf(lon,lat,pr(:,:,i_time)') If I understood the...

14 days ago | 1

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how to create noisy image based on Poisson's noise
Well poissrnd is what you want, as far as I understand. If you have an "ideal image" with intensity I: I = repmat(1+[0:11].^2,[...

14 days ago | 0

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How can I optimize function output by tuning 3 input parameters?
You'll have to modify (at least for simplicity) your function to something like this: function [Pressures] = myFunc(KpKdKi) ...

14 days ago | 0

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Getting Meters per Pixel out of the camera calibration app?
If you know the size of the squares on the checkerboard and your objects are at the same distance then you only need to count th...

14 days ago | 0

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How to specify points in on two curves in plot?
This seems like a task for interp1. Have a look at the help and documentation for that function. I'd do something like this: sc...

15 days ago | 0

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How do I generate a spherical image from a 3D matlab figure
Currently matlab has 'orthographic' and 'perspective' for the 'projection'-property of 3-D axes. You can perhaps get a wee bit ...

15 days ago | 0

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Nonscalar arrays of function handles are not allowed; use cell arrays instead.
You get the error in newton because the feval of your ydy-function returns function handles and you try to assign them to regula...

15 days ago | 0

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How to use smoothing spline to fit a closed curve?
You'll get some progress moving to radial coordinates (it will not be the same properties of a spline in radial coordinates as i...

16 days ago | 0

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how to delete elements in the matlab array by overcoming the Unable error to delete elements from this array because dimension 3 has fixed size.
In your function y will not be set. You only try to remove one element from the input, that's wasting time. When I run this at t...

16 days ago | 0

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When I attempt to run this code, it doesnt stop running. It will only stop when I pause it. Would appreciate any help as to how to fix this?
If your odes should have positive solutions (haven't checked them to be able to judge this), and they happen to become negative ...

17 days ago | 0

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earth magnetic field model
Check the help and documentation for whatever function you use to get the "world magnetic field". In the IGRF-implementation (an...

17 days ago | 0

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Much slower valid convolution using complementary size of kernels.
No, n-dimensional fourier-transforms, multiplication of the Fourier-transforms of 5-5-8 a with T will be a fair bit faster than ...

1 month ago | 0

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Curve Fitting for a function with 3 fitting parameters.
For this I typically use standard non-linear least-square-fitting. That only requires some optimisation-routine, like fminsearch...

1 month ago | 0

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polyfit with multiple dependent variables
The polyfit function only works for 1-D polynomials, as far as I understand things. However there is an n-dimensional polynomial...

1 month ago | 0

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MATLAB's crosscorr function and R Studio ccf show different results
If you cannot find the information in the documentation, you'll have to go to the source. This is what I find in the xcorr funct...

1 month ago | 0