Community Profile # Bjorn Gustavsson

### UIT, the Arctic University of Norway

Last seen: Today Active since 2001

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Convex Hull without the in-built function.
Take it step by step. 1, put points on paper. 2, work out how to step from the point with the smallest y-value to the next poi...

ungefär 19 timmar ago | 1

Newton Iteration using symbolic function
Since you use symbolic variables and do the calculations symbolically you will get a symbolic answer. Here you should convert y...

ungefär 23 timmar ago | 0

If I want to plot arrow in patch, what codes do I have to use? And is there any method by using quiver and patch together?
Can't you simply use either of these two file exchange contributions: arrow, arrow3. These are typically the functions I use whe...

en dag ago | 0

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Find Centroid of area with 4 pouints
You could make good use of this little piece of information: Centroid of a finite set of points HTH

6 dagar ago | 0

Problem taking curl of a vector field.
If your sampling-points fall on a nice plaid regular grid then just use reshape to convert X, Y, U and V into 2-D matrices and e...

7 dagar ago | 0

Using symbolic math to retain accuracy. Arrays
Factor out the average of each row of C. That should give you one term of the row-averages of C and then the sum of the logs of ...

7 dagar ago | 0

How to find index in multi-dimension matrix
You can do this in 2 simple steps: [xMax,idx1D] = max(X(:)); [i1,i2,i3,i4] = ind2sub(size(X),idx1D); HTH

12 dagar ago | 0

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Make an double integral function
By putting the product inside the first pair of square brackets you've made the formula look a little bit confusing - since the ...

13 dagar ago | 0

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adding random noise to an image for N times
The question is a bit too vague to be precisely answered. Image noise typically have some specific probability-distribution, pos...

16 dagar ago | 0

Picking data from graph?
If you have the signal S, the corresponding sample-times t and the start and stop-times t1 and t2 you can select the signal in t...

16 dagar ago | 0

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find onest and end of wave ?
You cannot in a strict sense. You will have to settle for the first and last wave-crest, or set some arbitrary threshold for the...

21 dagar ago | 0

How to segment image without losing information at the edges for finding centroid?
The only way I can imagine the meaning of centroid in a grayscale image like the one above is with the same definition as "centr...

22 dagar ago | 2

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How can I know more details about the function spap2?
Why don't you just try: edit spap2 From there you should be able to read for yourself. As far as I can see most functions are ...

22 dagar ago | 0

how to solve ODE that contains integration over time?
For this type of integro-differential equations the standard "first-stab" trick is to differentiate it one step, which should gi...

26 dagar ago | 0

Matlab mathematival modeling problem chemical eng
You have at least a couple of syntax errors in your code, namely the lines: 4*((dacetdt)^2)+10*dacetdt = racet; 4*((dAceticdt)...

26 dagar ago | 0

why there are two different comands for calculating convolution of two vectors?
The answer to: why returned: "To please all." That might be more of a matlab in-joke, but a true answer can only (possibly) b...

26 dagar ago | 0

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How to save/store/recuparate data from inside a nested loop.
This should be simple enough if you do something like this: Y_best = zeros(n_something,N_aoa); % Not clear to me what your Y co...

27 dagar ago | 0

Adding a legend to a Graph in Matlab
Would something like: legend([h(idx1(1)),h(idx1(2)),h(idx3(1))],... 'label1','label2','label3') work for this case. Here ...

28 dagar ago | 0

Does detrend function remove the mean of the signal?
If you read the help of detrend you will find: DETREND Remove a linear trend from a vector, usually for FFT processing. [...

30 dagar ago | 0

How to correct resonance phase plot
You could quick-fix this by plotting the phase-angle phi like: plot(unwrap(2*phi)/2) But you might have to check that you calc...

ungefär en månad ago | 0

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Tri-diagonal Matrix with varying diagonals
You have to set the elements of z to the values you want. In your version you set z to a new scalar (first time around the loop ...

ungefär en månad ago | 0

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Colormap on values related to bins
Perhaps you could use scatter to plot this. According to your description itseems as if you have a 2-D histogram type of data, b...

ungefär en månad ago | 0

How to include variable offsets in polynomial equations
Have a look at the help and documentation of taylor. That should help you a good part of the way - especially if you use the 'ex...

ungefär en månad ago | 0

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3 loops using sprintf to change directories doesn't quite work
Have a good look at the help and documentation of fullfile. That function is made to help you generate full filenames with absol...

ungefär en månad ago | 0

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I am not able to solve value of 3 constants with three equations
For given values of b, d, and L you have a standard system of linear equation. An obvious solution to these equations are all ci...

ungefär en månad ago | 0

How to use ode45 to solve coupled second order differential equations
It might be that your expectations on the modification of the beat in y, it might be something else. (When I converted the dsolv...

ungefär en månad ago | 0

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How to interpolate harmonic data series (without sin / cos equation defined)?
You should not "inpaint" data this way and then use that to extract SQ-curves or any such averaged quantities. You have the data...

ungefär en månad ago | 0

Solving coupled system of second order differential equations symbolically
Like the Greek godess used to say: Just do it!: y'' = k/m * y + w/m * z, z'' = J/I * z + w/I * y, syms t syms y(t) z(t) syms...

ungefär en månad ago | 0

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