Rik

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2 568 total contributions since 2017

E-mails with feedback/questions about FEX submissions are welcomed. In general I will post e-mails about Answers on the related page, unless there is good cause not to do so.

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Answered
How to calculate the center of white part?
The best way is to use something like regionprops, but since you only have a single patch, you can use find to get a list of coo...

2 dagar ago | 1

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Answered
how to plot a function
The same as any other function: find a vector of x data and calculate the y data. Then you can use plot. You can use plot3 for x...

3 dagar ago | 0

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Nominate yourself to become a member of MathWorks Community Advisory Board
You can find the current members of the MATLAB Central Community Advisory Board on this page. At the bottom of that page, you c...

3 dagar ago | 0

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Use API in matlab
You're in luck: NASA decided to provide the data in JSON, and Matlab can parse that JSON output for you: url='https://power.lar...

3 dagar ago | 0

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Deployed exe with configuration file
It sounds like you need something very similar to my GetWritableFolder function. You can use the second output to confirm the f...

3 dagar ago | 0

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Answered
simple calculator using GUI
For general advice and examples for how to create a GUI (and avoid using GUIDE), have look at this thread. Every callback is a ...

3 dagar ago | 0

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How I can optimize my code for a stack construct?
Dynamically growing a variable is generally slow, because Matlab needs to copy the entire array. You could pre-allocate a stack...

3 dagar ago | 0

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Subset of an array with a moving window
The code below relies on implicit expansion to create an index array, which replicates the results from the inner for-loop. Sinc...

6 dagar ago | 1

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Answered
How to make a simple grid of coordiantes ?
If you read the documentation, you can see how to plot vectors without plotting connecting lines. As for generating the coordin...

7 dagar ago | 1

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Merging existing subplots into a single one
This is a surprisingly difficult task. You will have to copy all objects to the same figure and adapt the Position properties of...

7 dagar ago | 0

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How to find the exact answer of an exponential equation?
You can use double to extract a numerical value, but if you're looking for a time, something is going wrong here. The numerical ...

7 dagar ago | 0

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How to find maximum value and corresponding x-value of multiple graphs?
This is trivial if you use an array instead of numbered variables: z{1}=zeros(numel(fv),1); z{2}=zeros(numel(fv),1); z{3}=zer...

7 dagar ago | 0

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Answered
Tips on combining while loop
You were creating a function, why not make that explicit? %Pohlhausen/thwaites polynomial %clear;clc;close; % ^^^^^^ you do...

8 dagar ago | 0

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Strange behavior of if statement
Welcome to floating point integers. Matlab stores these numbers in a binary representation with a finite precision. Similar to ...

8 dagar ago | 0

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Answered
Create interface to control my instruments.
For general advice and examples for how to create a GUI (and avoid using GUIDE), have look at this thread. You can use a callba...

9 dagar ago | 0

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How to split .mat data into different variables?
You can't have a file in your workspace, only variables (and objects if you don't count those as variables). There are some gue...

9 dagar ago | 0

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Can you have a function for multiple scripts that are growing in size?
Scripts are not for real work, use functions instead. Functions allow you to write code that solves a specific problem. You can ...

9 dagar ago | 0

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Error in saveas, invalid or missing path
You should create a path from parts by using fullfile. That way you avoid having to think yourself about which filesep to use. ...

9 dagar ago | 0

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find the row and column value of a specific value in cell array
You need to use a bit of trickery to use find (ismember will not work normally either). cellarr = {... 'a','b','c', 3 ,5;....

10 dagar ago | 1

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Write and format table to csv file
You can use formattedDisplayText (which was introduced in R2021a). (see this highlight for an extra example) For older releases...

10 dagar ago | 0

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How do you check if an inputed number is an array/vector or just 1 value?
In my view using numel or isscalar (introduced somewhere between v6.5 and v7.1) would be a better solution. xscalar = numel(x)~...

11 dagar ago | 0

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Help with if statement in a calculation loop
The problem is that you assume Matlab will process each element of x separately. Matlab will only do that if you use a loop. ...

11 dagar ago | 0

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Can I open a file made in R2019a with different versions of matlab (R2017b)?
This depends on what kind of file you're talking about. mat files and m files are very portable, especially if you leave the def...

14 dagar ago | 0

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Answered
Comparing values of a vector
This is the easiest way to do it vectorized: Zc_0_to_P =@(x) (M/P^2)*(2*P.*x - x.^2); % 0≤x≤P Zc_P_to_1 =@(x) (M/(1-P)^2)*((1-...

14 dagar ago | 0

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Answered
Version number 2021a Version='9.10' is confusing. Why not using '10.0'
Versioning is a complex and hotly debated topic. Generally you want to increment the first number if you have a really big upgra...

15 dagar ago | 0

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Answered
Assign date values manually to datetime array matlab
For pre-R2020b, you can use readfile, which you can get readfile from the FEX. If you are using R2017a or later, you can also ge...

15 dagar ago | 1

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Answered
courbe de progression du pixel
%load an example image S=load('mri'); I=squeeze(S.D); x=randi(size(I,1));y=randi(size(I,2)); intensity=squeeze(I(x,y,:)); ...

15 dagar ago | 0

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Answered
modify a program to obtain the same result from right to left
Your loop can probably be replaced by a vectorized operation, but I will leave that for you to figure out. I suspect fliplr and ...

16 dagar ago | 0

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How to use output numbers as a vector.
There are may sorting algorithms you could implement. One of the easiest to implement (and one of the slowest) is called bubble ...

17 dagar ago | 1

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Answered
When I attempt to run this it produces an 'error using zeros, size inputs must be integers' for the line DcDt = zeros(n,1). The code is supposed to produce a breakthrough curve. Any help is appreciated.
L is not defined. If it is smaller than 0, this will lead to z being empty, meaning that n is 0. L=-1; z=0:0.001:L; numel(z) ...

17 dagar ago | 0

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