Bjorn Gustavsson

UIT, the Arctic University of Norway

Last seen: Today | Active since 2001

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How to write a code for plotting a Poincare map for the analysis of a double pendulum and also How to simulate the motion of the double pendulum.
You will find a couple of contributions on the file exchange for Poincare-maps, the first seems promising: FEX-hits on "poincare...

17 hours ago | 0

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area of water body in a grey color image
If the water-surface are flatter than the not-water-surfaces (seems reasonable assumption for standard optical satellite imaging...

1 day ago | 0

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solve a complex second order differential equation
The first step is to convert your second-order ODE to two coupled first-order ODEs: Then you should write that ODE-system as ...

3 days ago | 0

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2D Minimization problem, not good for fminsearch?
For problems like these (It seems likely that your function has multiple local minima or at least very very flat regions) the be...

4 days ago | 0

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Error using * Incorrect dimensions
For problems like these you should learn to run the code line-by-line at the command-line prompt. Then check the size and type o...

4 days ago | 0

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Can someone please drop the code for ICA( independent component analysis) for image segmentation on matlab for classifying thermal images
Look on the file exchange for ICA-implementations: ICA at FEX Get fastICA from the/(a significant) source: FastICA Then the ma...

4 days ago | 0

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Integer eigenvalues in Matlab
Since you have a matrix and want the eigenvalues then the best approach seems to be to actually calculate the eigenvalues. For t...

8 days ago | 0

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How to solve simultaneous equations?
Using symbolic tools you have solve - look at the help and documentation for that function for examlpes. Your problem should red...

9 days ago | 0

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How to extract data from a function or functions. Also how to export this data to excel.
Your functions have their own name-space where the variables that are defined exists (in addition to the input variables that yo...

9 days ago | 1

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how to Solve 4 Equation and 3 unknown
When you have four non-linear equations with three unknowns you cannot, in general, expect to get a symbolic solution. For these...

10 days ago | 0

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fitting data to system of ode
You will find the answer to this problem in a link to yet another answer (by Star Strider) here: fit-a-parameterised-ode-solutio...

10 days ago | 0

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How to solve differential equations with varying constants
For the case you describe you have to add information about how X and p varies with time. Are they constant over some fixed inte...

10 days ago | 0

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What should go in a next-generation MATLAB X?
Allow elementary mathematical operations on function-handles. So instead of writing the sum of two functions as: f1 = @(x) x.^2...

11 days ago | 0

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Plotting spectrograms for multiple files
Wouldn't you achieve the desired output by putting the different spectrograms in consecutive subplots? Something like this perh...

17 days ago | 0

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How to define constraint in Optimization such that difference in value between two consecutive unknowns is not greater than 50%
Perhaps a constraint-function like this would get the job done (might be used with fmincon for example): function [c,ceq] = you...

17 days ago | 0

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Using fsolve to solve equation system for coefficients of a Schwartz-Christoffel map
You can use the optimization-functions to get a solution, or a hopefully good starting-point for fsolve. If you define a sum-of-...

17 days ago | 1

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Plot handle not being assigned
When you plot multiple lines plot returns an array of line-handles then it doesn't work to assign those to one element in h. For...

17 days ago | 0

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Solving a pair of equation using matlab
You have 2 unknown parameters k and theta. You have one condition for y at t=0 and one condition for dy/dt at t=0. Since you hav...

18 days ago | 0

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perpendicular and parallel component
You have to look at the documentation of the mission and the data access etc: MMS_Data_Access_f3. We cannot tell you how to hand...

24 days ago | 0

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topograph created by EEGLAB using ERP
For this you could do something like this (except I will use random data and plain imagesc): I_peaks = rand(3,1); for i1 = 3:-...

25 days ago | 0

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Wrong distortion parameters in camera calibration
After quickly looking at the amount of distortion noticeable it seems pretty small - open the images in gimp (for example, comer...

26 days ago | 0

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How to use one marker for looped plots in legend
To get full controll of legends use the graphics-handles that are returned from the plot-functions. Perhaps something like this:...

1 month ago | 0

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How to determine the coefficient from the argmin function ?
This is a standard minimization-problem, for that matlab has the fminsearch function (and possibly a couple more in the optimiza...

1 month ago | 0

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Roughness of 3D Surface
There are a number of hits returned when searching for "curvature" on the file exchange. The gptoolbox seems to have a bunch of ...

1 month ago | 0

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How to range array steps
Split into two sequences: x = [-1:-1:-32,32:-1:1]; HTH

1 month ago | 1

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How to implement Hermite spline in Simulink
There is a way to make blocks that wrap a matlab-function (matlab-functions-simulink_5), shouldn't that solve this task? HTH

1 month ago | 1

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Answered
Speed Up the for loop
A couple of suggestions: 0, check the time spent on different lines by running this script with smaller limits on j and i with ...

1 month ago | 1

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Principal component regression, keeping variable names
Well the eigen-vectors will correspond to some linear combinations of your orignal variables. As such one eigenvector might for ...

1 month ago | 1

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Solving coupled differential equations.
The first trick to try with these coupled integro-differential equations is to try to "differentiate away the integrals": whi...

1 month ago | 0

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How can I obtain the Fourier Transformation as a product of matrices?
Have a look at the help and documentation for dftmtx. That function should return the discrete Fourier-transform matrix and give...

1 month ago | 0