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Bjorn Gustavsson


UIT, the Arctic University of Norway

Last seen: Today Active since 2001

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Answered
Generate nchoosek vectors line-by-line
There are loads of nchoosek functions available on the file exchange: nchoosek. Some of those should help you with this. I recal...

1 day ago | 0

Answered
Parameter Estimates for Ordinary Differential Equation
Solve the ODE analytically. That will give you an expression for T(t,c1) this you can then use for a standart non-linear least-s...

1 day ago | 0

Answered
3D Polar Plot
A quick search on the file exchange leads to these submissions:pcolor-in-polar-coordinates, 3d-polar-plot and polar-contour-plot...

2 days ago | 0

Answered
Struggling trying to create a 2-D contour plot from a large data set from x and y coordinates and corresponding frequency value
Wouldn't something like this do: % Mock-up of data similar to yours... x = linspace(-5,5,501); y0 = linspace(-2,2,201); [x,y...

2 days ago | 0

Answered
Add legend for a specific plot
Explicitly use the handles returned from the plotting-functions: legend([l1(:);l2(:);l3(:)],'text1_1','text1_2','and','so','on'...

2 days ago | 0

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Answered
Solve differential equation from Matlab
For a numerical integration of this ODE look at the help and documentation for ode45 and its siblings, also look at the examples...

2 days ago | 0

Answered
How to smoothen contourf plot to make it look better
Best way (probably) to go about making your contourlines smoother is to interpolate your data: Xi = linspace(min(X(:)),max(X(:)...

4 days ago | 0

Answered
variable number of if condition
Maybe something like this: for i = min:max %:columns b = 1; d = 1; f = 1; for a = 1:length(Ex) for i_c...

4 days ago | 0

Answered
Why does this code generate a mix of integers and doubles?
In practice you can look on this problem as "good luck" and "bad luck" when it comes to working and not working. The rounding of...

4 days ago | 0

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Answered
Remove noise from the image
First start by trying standard filtering-methods. Compare what you get with 2-D median-filter (medfilt2), and Lee's sigma-filter...

6 days ago | 0

Answered
Function GUNZIP was unable to read URL ''http://opihi.cs.uvic.ca/sound/genres.tar.gz''.
If the file doesn't exist then nothing will be able to read it. I wouldn't bother using gunzip, I'd go for straight downloading ...

7 days ago | 0

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Answered
True north-based azimuths
Your question doesn't make much sense, sure you can do that - but that would be more of "establishing" your azimuth-convention. ...

7 days ago | 0

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Answered
Incorrect dimensions for raising a matrix to a power
Just set a debug-stop in that function and check what dimensions your variables have: dbstop in gaussh Or just at the point wh...

9 days ago | 0

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Answered
Filtering the large precipitation data for finding rainfall events
If you store your rain-fall-data in an array, r_f for rain_falls, with n_t rows and n_stations columns you could easily do thing...

9 days ago | 1

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Answered
How to fit regression
This is not a polynomial, therefore you cannot use polyfit. You can seamlessly use any least-square fitting routine to fit your ...

9 days ago | 0

Answered
curve of best fit
In order to get a function that has two y-values for for some range of x-values you will cannot fit a polynomial such that y=p(x...

10 days ago | 1

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Answered
how can compute a marginal distribution?
Look at the help and documentation for the histogram-function. Possibly also check the histogram2. HTH

10 days ago | 0

Answered
Solving a system of linear equations with lots of o coefficients.
Matlab is designed to solve systems of linear equations. It is one of the fundamental operators of its matrix-algebra: % Your p...

11 days ago | 0

Answered
Reading and analysing files in subfolders - indexing
Why not skip the generation of FileName and index into files directly inside the loop: dt = 0.005; tt = 0:dt:60; files = dir(...

11 days ago | 0

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Answered
Trajectorys of 4 objects on 3D plane not symmetrical
Your main problem (or rather: step to take) is that you do the calculations element-by-element in the different arrays. That is ...

13 days ago | 0

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Answered
Trying to use central difference scheme to solve logistic equation
Well run your code line-by-line and figure out what the problem is. This is what you let us know about your script (My comments...

16 days ago | 1

Answered
How to calculate jacobian matrix for R^n X R^n system in matlab
Maybe this illustration of how to reshape your variable x and function f from n-by-n to n^2-by-1: syms x [2,2] % a small n-by-n...

16 days ago | 0

Answered
Plotting 2 functions on the same graph
Skip the calls to subplot? That would make your scrip "not put the graphs in 2 separate axes": x1 = Pos1(t); x2 = Pos2(t); ph...

17 days ago | 0

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Answered
How does Matlab uses memory inside a function?
Matlab is very clever in memory usage in functions, pass-by-reference-copy-on-modification. So as long as you only take values o...

17 days ago | 0

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Answered
Using Shooting Method on Euler Method to Solve Second Order BVP
To do that you should make functions out of this script. That way you will have a much cleaner programme, that is far easier to ...

18 days ago | 1

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Answered
Mapping toolbox: irregular measured geo referenced data into regular grid
"5m" sounds like a reasonably small region of data? If so, local topography might be more important than the curvature of Earth....

20 days ago | 0

Answered
Pseudo-spectral method solution for wave equation PDE: d^2p/dt^2=(c^2)*[d^2p/dx^2 + d^2p/dy^2 + d^2p/dz^2]
This is just a linear wave-equation with constant speed of the waves. The general solution is just: So you just have to deter...

20 days ago | 0

Answered
How i can solve limit this ODE question .
This is a Riccati equation. Convert it to a standard linear second-order differential equation and solve it that way, check what...

22 days ago | 0

Answered
extrapolation of contour data set
Since the minimum value of your counttest-variable is 0.0853 or thereabouts you will never get any contour for levels lower than...

23 days ago | 0

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Answered
Solving an ode for newton with vectors
The thing you have to fix here is the indexing of r in your equation-of-motion. You have to extract the 3 velcity-components for...

29 days ago | 0

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