Community Profile # Bjorn Gustavsson

### UIT, the Arctic University of Norway

Last seen: 2 días ago Active since 2001

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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 ...

3 días ago | 1

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 ...

3 días ago | 1

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

4 días ago | 0

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...

4 días ago | 0

Solving non linear equation "Circle" equations
If the 20 equations are of the same form you will have a vastly overdetermined problem (that in general will not have any exact ...

4 días ago | 0

How can we plot the correlation
It seems that you ask for the corrcoef. If you look at the correlation between 2 signals you will simly get a 2-by-2 matrix whic...

5 días ago | 0

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how to solve a non linear ode equation ?
You have a quadratic equation for dCAdt, solve that one as a standard quadratic equation, you will end up with two solutions for...

5 días ago | 0

Implementing Runge kutta method in place of ode45
You simply take the RK-scheme that suits your preferences and needs, for example from: Runge-Kutta methods, and plug that into a...

5 días ago | 0

Can Ode 45 solve piecewise function in the iteration？
Your best approach is to use the events-handling procedure to interupt and restart the ode-integration whenever x and y passes t...

6 días ago | 0

Many 2D histograms, single colorbar
For that type of equalization I do someething like this: for i1 = 1:4 numberPairs(i1).matrix = randn(1000,2); subplot (2,...

11 días ago | 0

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Find centroid of curve
Something like this ought to work: [~,iEnd] = max(spline_pts(1,:)); [~,iStart] = max(spline_pts(2,:)); R1 = spline_pts(:,iS...

11 días ago | 0

Generate random number between -Inf and 0.5
Since the cummulative-distribution-function of the random-number-distribution has to be one at +infinity, you need to have some ...

11 días ago | 0

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Early exit instead of a warning in ODE113?
The brute-forciest way to do this might be to give ode113 an event that interrupts after some suitably long time, i.e. long enou...

13 días ago | 0

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Efficient ODE with function handles
If the function-handle-argument is too costly and you still want "some general flexibility" you might try to simply extend the O...

16 días ago | 1

How to specify the color of this contourf plot?
Maybe you can avoid the problem by using fill or patch by extracting the coordinates of the perimeters of the landmask? Somethi...

16 días ago | 0

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Multidimensional lookup table using griddedInterpolant
If you calculate all the combinations of points you dont need to go over the allcomb way, you could just as well run ndgrid at o...

16 días ago | 0

How to solve this Projectile Motion Problem
You write down the equation of motion: taking into account as many physical effects as necessary (gravity, drag) to get a sol...

17 días ago | 0

Interpolation of circular data
To my understanding simply extend the input arrays such that you have a couple of points from the first few samples added onto t...

18 días ago | 1

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How to enter and define a function with the value of one input form the order of matrix for another input
If you need a function with a bit more complexity than "a one-liner" simply write it as an m-function file. Then you can do pret...

18 días ago | 0

How can I plot a straight line from a curve?
To plot a line between a point [x_i,y_i] and [0,0] simply do this: ph0p = plot([0,x_i],[0,y_i]); Then you can decorate the lin...

18 días ago | 0

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For inbuilt solvers ODE23/DDE23, how to keep saving/output all solution values intermediately (eg: every 1 hour, save/output the solution instead of only after reaching tf)
You could request output for a selected set of points in time instead of only setting the time-span: t_all = [0:1:500]; [t_out...

19 días ago | 0

How can I add single vertical data cursor for all subplots ?
If you search on the file exchange you will find vertical-line FEX search-results, at a first glance at least the 4th and 6th su...

19 días ago | 0

How can i solve this optimization problem?
Best route might be to properly differentiate J with respect to delta_Uk and solve the normal equations and find an analytical s...

19 días ago | 2

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Solving system of ODE's contains complex equations
The way it looks to me you have a problem something like this: One problem is that the B-matrix you've given is singular whic...

19 días ago | 0

Scattered point clouds for pairs of arays
Have a look at the help and documentation for scatter. If you have very many points you might consider using histogram to get an...

24 días ago | 1

Fit using nlinfit with uncertainties on x and y accounted for in the fit
Have a look at the total least squares tools on the file exchange: total-least-squares-with-mixed-and-or-weighted-disturbances a...

25 días ago | 1

Best Descriptor for goodness of fit
The best descriptor for goodness of fit is some measure of the divergence between the distribution of residuals of your fit and ...

26 días ago | 0

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How to plot a contour diagram?
You should be able to do that with pcolor-in-polar-coordinates. Perhaps you might need to lightly modify the function to exactly...

27 días ago | 0

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Creating a vector from a set of coordinates
If you do: r = [x(:),y(:)]; % (:) forms column-vectors of any-dimensional array. Then you will find: p1 = r(1,:) HTH

30 días ago | 0

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