# Bjorn Gustavsson

### UIT, the Arctic University of Norway

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Question

matlabpath - order not respected?

In one of the toolboxes I have downloaded there are some functions (erf, gamma) that are shading the corresponding built-in func...

8 months ago | 1 answer | 1

### 1

answerHow to fit ODE curve using loop?

Have a look at the answers to this question: ode-with-best-fit-adjustment-to-empirical-observations monod-kinetics-and-curve-f...

1 year ago | 0

Fanbeam command projection directions and attributions clarification

The way I interpret the help and documentation the vertex with the source are located at negative y for rotation-angle zero. For...

1 year ago | 1

| accepted

Error in using ode45 for solution of nonlinear system of three equations which are interlinked to each other

Perhaps you need to check the size of each component in your ode-function: f = @(t,x) [-(p1 + x(2)) * x(1) + p1 * Gb + D; -p2 *...

1 year ago | 0

Image processing and contour differentiation

This seems to be a problem where you could use the file exchange submission: distance2curve. Just brute-force loop over every po...

1 year ago | 0

Excluding noise from a curve

Perhaps you will have to combine a number of criteria: 1, if you have a peak for x<300 2, and is above some threshold 3, and ...

1 year ago | 0

Plot contour with "concave" XY coordinates

NOTE: edited so that the code runs here and displays the results CL The problem happens because griddata (and both scatteredInt...

1 year ago | 0

How to loop through a specific file in various subfolders inside a main folder?

For this I (sometimes) do this type of thing: proj_root_dir = '/full/path/to/project'; data_dirs = {'damage1_case20','damage2_...

1 year ago | 1

How to define for which plane lies a given point with coordinates?

This is easiest to do with a vector-algebra approach. Something like this: 1, the plane can be described as all points such th...

1 year ago | 0

| accepted

How to define legend (or assign arrows to each plot)?

Use the output from plot. Something like this: %Analytical solution of Duffing equation %% Matlab code to find the frequency r...

1 year ago | 0

How to run multiple Matlab codes one after other even if one middle code will stop due to error?

You can try something like this: n_p = 5; run_status = zeros(n_p,1); try one run_status(1) = 1; catch run_status(1)...

1 year ago | 1

Solving differential equation using matlab

Do step-by-step and avoid using strings, like this: syms t real syms x(t) Dx = diff(x); D2x = diff(x,2); y = dsolve(D2x ...

1 year ago | 0

How can I find the angle between two vectors that answer should be between 0 to 2*pi

This question has been answered several times: angle-betwen-two-3d-vectors-in-the-range-0-360-degree, angle-between-two-vectors...

1 year ago | 0

| accepted

Contour plot: distorted contours and blank spaces in plots.

The reason you get these jagged contour-lines is that the triangulation-based interpolation you use is based on a Delaunay-trian...

1 year ago | 0

Non-pixelized image using imagesc (or alternatives)

That was not an immage you linked to but rather a movie (at a push a sequence of images). The first frame seemed reasonably simi...

1 year ago | 0

changing ticks position on the graph

If you have coordinates for the edges of the cdata-elements then you can either adjust things manually to get what you want: dx...

1 year ago | 0

mis match matrix dimension

As the commenters have indicated your request is to non-specific to have one solution, while we all expect you to have one speci...

1 year ago | 1

| accepted

Take the derivative of a SYMBOLIC Matrix with respect to a Vector

You might get close enough with jacobian to get the full output: syms x y real % simple 2 x 2 matrix: M = [sin(x+y) cos(x*y);...

1 year ago | 1

| accepted

Calculating the eigenvalues of simple shapes

If you have a binary image then why not just run through the svd and see what you get: I = zeros(256); I(64:(64+128),64:(64+12...

1 year ago | 0

Use of ODE45 for concentration plot help

To the best of my understanding you should include all three species in the ode-function. Perhaps something like this: function...

1 year ago | 0

How to describe loop for my ODE equations?

Write a function for these coupled ODEs. Inside that function you can use all the normal programmig tools and tricks you can thi...

1 year ago | 0

| accepted

Locking the Legend even if the object is deleted

If you explicitly set the axis of the plot, then you can hide objects outside the visible are and use their handles for the lege...

1 year ago | 0

Neural network for curve fitting (estimating function parameters)

In any type of parameter fitting problem you're facing the curse of dimensionality in one form or the other, because the number ...

1 year ago | 1

Image analysis for speckle pattern

A couple of things I'd try would be to determine the size-distribution of the speckles at different intensity-levels. This I'd d...

1 year ago | 0

Multiple curve fitting via optimization

For this type of problem I would use lsqnonlin, so read the help and documentation of that function and what additinoally you ne...

1 year ago | 2

| accepted

Why cant I get a stable Cranck Nicolson discretization?

(caveat: I didn't run your code or analyze it, but speak from my experience with CN) Most likely you take too long steps in time...

1 year ago | 0

Passing a matrix between several callbacks

If you have all your user interface in one figure (some calculator-like programme), then one way to store the matrix is in the '...

1 year ago | 0

Joint Probability Density estimation function

Search the excellent File Exchange for everything you need but cannot find in your matlab-installation! Here's what comes up wh...

1 year ago | 0

Integrating a line integral e^x(sinydx + cosydy) over an ellipse 4(x+1)^2 + 9(y-3)^2 = 36

For the integration you should use Green's theorem. It is beautiful, especially for this case. For the vector-field-plot you ca...

1 year ago | 2

| accepted

How to calculate a double integral inside the domain of intersection of two functions?

Perhaps you can use Green's theorem (you'd be very lucky if you could - but if you were to be that lucky in this case it would b...

1 year ago | 0