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Bjorn Gustavsson


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UIT, the Arctic University of Norway

1.105 total contributions since 2001

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Answered
Local macro in STATA?
That is generally a poor programming pattern (read this as: "This is a really poor idea!"). You should aim to write your code su...

ongeveer 20 uur ago | 0

Answered
function for addition 2^16 modulo
Just make sure that your ints a and b are in int32 or larger number of bit-formats, then use: C = mod(a+b,2^16) HTH

1 dag ago | 1

Answered
how do I classify image based on smoothness and high frequency?
For measure of smoothness I'd go with something like this: d2I = del2(I); % laplacian of your image (grayscale, double). From ...

2 dagen ago | 0

Answered
Horizontal First Differencer on a Matrix
Have a look on the help and documentation to diff. For this case use: y = diff(x,[],2); % or explicitly 1st difference: y = d...

3 dagen ago | 0

| accepted

Answered
How to remove space between subplots of heatmaps?
If you use the axes-handle output from subplot you can then set any of their properties as you desire: sph = subplot(3,1,1); %...

3 dagen ago | 0

Answered
If a structure exists in a file
You can explicitly check for the existense of a variable in a .mat-file: qwe = whos('-file','your-filename.mat','cDA_External_S...

3 dagen ago | 0

| accepted

Answered
help debugging 3-D plot code
You have to get your equations for x, y and z right: x = a*cos(phi).*sin(theta); y = b*sin(phi).*sin(theta); z = b*cos(theta)...

3 dagen ago | 1

| accepted

Answered
Combined mean monthly values from 24 years of monthly data
Something like this perhaps: BV = table2array(baseline_values); clf subplot(2,1,1) imagesc(reshape(BV(:,4),12,[])') % Illust...

4 dagen ago | 0

Answered
Plotting negative values on an histogram
It seems likely that you've mixed up BinCounts and BinEdges - it doesn't make much sense to have a negative number of something ...

4 dagen ago | 0

Answered
M-point averaging filter to an image
Read the help and documentation for conv2. HTH

4 dagen ago | 0

Answered
Why doesn't the ode15s solver work when I switch 'k1q','k2q','k12q' from a single value into vectors(more values)?
When k1q is an array you will get an error when you try to assign the product of that array with the scalar C(1) to dCdt(1) whic...

4 dagen ago | 1

| accepted

Answered
i am getting error in line 18 of invalid use of operator.please help me solving this
OK, so you want to solve 3 coupled equations of motion for some harmonically varying solution. First you have to understand the ...

6 dagen ago | 0

Answered
make a better map
You should try: shading flat instead of the interp option. You will have to accept the fact that you only have data in a 32-by...

6 dagen ago | 0

| accepted

Answered
Solving differential equations to get accurate plot as shown.
Since you get an oscillatory behaviour of (primarily) Cecm and Crec it is very likely that you have a bug for some of the reacti...

6 dagen ago | 0

Answered
How to use chebop function?
Have you installed the chebfun package? Have you added the chebfun install directory to the matlab-path? If you have it install...

7 dagen ago | 0

| accepted

Answered
Improving speed of readtable
It is a rather large data-file to read. You might reduce the read-time if you use load instead of readtable - that should reduce...

7 dagen ago | 0

Answered
How to create and plot an oloid in MATLAB
Have a look at the help and documentation of the convhull function. That should give you a solution for this task - in the sense...

7 dagen ago | 0

Answered
Multidimensional integration in matlab
Have a look at the help and documentation for integral2. That should be the function to do 2-D integrals, that sounds like the f...

8 dagen ago | 1

Answered
Why does version R2020b gives errors when running functions such as fmincon, when version R2019a runs properly.
Have you installed the optimization toolbox in your 2020b install? If not that is where that function resides. Check the existe...

8 dagen ago | 0

| accepted

Answered
Simulation of Shepp Logan phaton dataset
The phantom-function is a standard .m-function available in source-code, so you can read it clean and plain. It is simply a func...

9 dagen ago | 2

Answered
Different line types for multiple curves
Maybe you'll have to accept looping a little: lstl = {'-','--'}; for i1 = 1:4, set(p(i1),'linestyle',lstl{rem(i1,2)+1}) en...

12 dagen ago | 0

| accepted

Answered
Inputs must be floats, namely single or double.
When you integrate an ODE numerically there is no need whatsoever to introduce a declaration of T as a symbolic variable (the wa...

12 dagen ago | 1

Answered
error occurring while solving odes using ode15s
Check your mass-matrix E and make sure it looks exactly like you expect. The 3 off-diagonal 1s looks peculiar to me. Then you ha...

13 dagen ago | 0

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Answered
Find Peaks error - Expected X to be strictly increasing
Check that your X-variable is actually monotonically increasing (you might have replicate points, which then messes everything u...

14 dagen ago | 0

Answered
The legend does not show the right marker:
When using legend it is always preferable to use an array of handles returned from the plotting functions. Try something like: ...

15 dagen ago | 0

| accepted

Answered
stft for complex data
Shouldn't that be as simle as: Acmplx = I + 1i*Q; spec = fft(Acmplx); % or spectrogram etc HTH

15 dagen ago | 0

Answered
How do I interpolate in 5d?
Have a look at the help and documentation for interpn. HTH

15 dagen ago | 0

Answered
Sparse matrix from the columns of an initial matrix
Something like this might work: vals = []; idx1 = []; idx2 = []; for j = 1:n idx1 = [idx1,1:n]; c...

16 dagen ago | 0

Answered
Is there a way to adaptively sample 2-D surfaces ?
It is not entirely clear what your "problem situation" or "design desires" are. These might be very important for what type of s...

16 dagen ago | 0

Answered
Error using odearguments (line 21) When the first argument to ode23s is a function handle, the tspan argument must have at least two elements.
Your t variable will only have one component as you define it. My guess is that you want 100 elements between 0 and 1. If that's...

26 dagen ago | 0

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