Rik

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2,561 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
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...

1 day 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...

1 day 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...

1 day 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 ...

1 day 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...

1 day 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...

2 days 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 ...

3 days ago | 0

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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...

3 days 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...

4 days 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 ...

4 days 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. ...

4 days 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;....

4 days ago | 1

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Answered
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...

5 days 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)~...

5 days 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. ...

5 days 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...

8 days 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-...

9 days 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...

9 days 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...

10 days 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,:)); ...

10 days 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 ...

11 days 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 ...

12 days 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) ...

12 days ago | 0

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Displaying an array of zeroes.
doc fprintf

12 days ago | 0

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Evaluating function on an array of values
There are several problems here. The main one is that you are using matrix operations instead of element-wise division. In this ...

12 days ago | 0

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Saving data to current date
doc datetime

13 days ago | 0

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Using student license on more than one computer
Since a student license is a personal license (and only allows installation on 1 computer), there are two problems with your pla...

16 days ago | 0

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str2num returning value while the preferred str2double returning NaN...
This is another difference: str2double('evalc(''exit'')') str2num('evalc(''exit'')') %will exit Matlab You should parse the ...

16 days ago | 0

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Answered
Is it possible to vectorize this simple recursive function in loop?
Vectorization should only be attempted if there are more direct functions. Otherwise, for loops in Matlab are surprisingly optim...

16 days ago | 3

Answered
Writing data from GUI handles to text file
(the advice I wanted to post became a bit long, so I will put it in an answer instead of a comment) My general advice for writi...

18 days ago | 1