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Rik Wisselink


988 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 do I fix this
You are using t as an index to m_t, but that contains negative values. (in the call to trapz) I suspect you want to run the lin...

16 hours ago | 0

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Answered
MATLAB Answers Wish-list #4 (and bug reports)
If a question is closed, you cannot write a comment anymore. E.g. this question was already closed, but since it was the first q...

18 hours ago | 0

Answered
I have a code but it keep saying "invalid expression. when calling a function or indexing a variable, use parentheses. otherwise check for mismatched delimiters.
You are using square brackets for the sin function, instead of parentheses. Also, you were missing a lot of * signs. You should ...

18 hours ago | 1

Answered
MATLAB Answers Wish-list #4 (and bug reports)
Since the new editor has become way more fancy: A while back I read in some help page for the Answers forum that a referrence t...

1 day ago | 2

Answered
Converting the program to the GUI version
There are many ways to share data between callbacks. In the context of GUIs the most often used function is guidata. You can al...

1 day ago | 0

Answered
Hi there, I need to create a code that can replace the diagonal values on a matrix with 0's..
A=rand(5,5); A(size(A,2):(size(A,2)-1):(numel(A)-1))=0

5 days ago | 1

Answered
Using xlsread in a for loop
If the worksheet names are 0.600 etc you can use the code below. B=struct; for n=20:-1:1 A= xlsread(filename,spri...

7 days ago | 1

Answered
How to calculate 3D Positions using the distance from 3 separate points in space?
You could use something like the code below. It uses only base Matlab functions to search a position where the radii of your mea...

10 days ago | 0

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Answered
it says it has an untitled error in line 6 which i think it's about clause of if
You made the mistake of using |i| and |j| as variables and you forgot to initialize |j|. Also, think about what this code doe...

10 days ago | 0

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Answered
How can I calculate the area between two curves?
The |polyarea| function handles this just fine. figure(1),clf(1) x=0:1500; y1=@(x)(100./0.93).*(((x./19).^(10))./(1+(...

12 days ago | 0

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Answered
is it possible to write a code that experiments with zero mean Gaussian noise for a variance in the range 0.001 to 0.1
Yes, this is what for loops exist for. variance_list=.001:.001:0.01; for k=1:numel(variance_list) J = imnoise(MEANPIC...

12 days ago | 0

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Answered
How to change elements in several arbitrary positions at the same time
You can use the |sub2ind| function (I used the |bsxfun| function to generate the row numbers) A=[0 0 0 0; 0 0 0 0; 0 0 0 0]...

15 days ago | 0

Answered
MATLAB integer to roman numeral
I wouldn't hard-code the combinations, but use the rule instead. My proposal would look something like this: # convert the ch...

16 days ago | 1

Answered
Assignment has more non-singleton rhs dimensions than non-singleton subscripts
|find| is not guaranteed to result 1 value. It might return a vector, or an empty array. If you are certain there will always be...

16 days ago | 0

Answered
Finding the index of a matrix corresponding to a particular column of another matrix
You can try this: A= [4 12 ; 2 6]; B = [9 4 8 12 ; 2 2 4 6]; selected_col=1; col_in_B=find(all(A(:,selected_col)==...

17 days ago | 1

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Answered
Finding R squared in a loop
Just a quick note: a negative R-squared is actually possible. It just means your fit is so bad it is even worse than using the m...

17 days ago | 2

Answered
Keep prompting user instead of hitting run each time.
You can wrap your code in a while loop, but that will force the user to hard-break out of your code (ctrl-C on Windows). A nicer...

17 days ago | 0

Answered
How can I create 3D pixels image
The code generating the binary mask is relatively easy to extend, but you'll have to think about the image format you want to sa...

21 days ago | 1

Answered
Gui appears and disappears before user can do anything with it
It is not because the figure is not visible yet, but because the GUI figure is not a callback figure at that point (at the most ...

23 days ago | 0

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Answered
Calculate residuals as a single number in lsqnonlin function
Yes, the sum of squares or the RMS: SSq=sum(res.^2); RMS=sqrt(mean(res.^2)); The downside of using the plain sum is t...

23 days ago | 1

Answered
Call OpeningFcn each time a button is pressed
There are two strategies I described: # Have a function that you call at the end of |OpeningFcn|. That function only call |ui...

24 days ago | 0

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Answered
i have used dwt2 function for my input image? for approximation level i am getting blank image. what sould i do ?
Your image is not white. |imshow| assumes your data is scaled from 0 to 1 if it is a double, while your data is clearly not from...

24 days ago | 0

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Answered
Encryption scheme operands?
You forgot a space in your definition: Alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ '; numbers = [1,12,7,5,2;18,1,27,27,27]; ...

24 days ago | 0

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Answered
nearest tangent point from Ginput point to line ?
My <https://www.mathworks.com/matlabcentral/fileexchange/64396-point-to-line-distance FEX submission> should help here. Unlike w...

25 days ago | 0

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Answered
How to modify this code for true result?
Your algorithm might not always result in an optimal packing. You should start with the biggest box and go down in volume. That ...

26 days ago | 1

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Answered
Change matrix size for each successive experiment
Don't use |i| as a loop index, it may cause confusion/bugs and is trivial to avoid. m=1; for n = 101:100:2100 k =...

26 days ago | 0

Answered
Help me Understand why my First Array Index is invalid
You also have a warning in the lint on this line. The mlint is a very useful tool in debugging, so you should make sure you have...

26 days ago | 0

Answered
XTicklabels don‘t match
If you want full control over the ticks, you must set both the ticks and their labels explicitly. If you don't, it may depend on...

26 days ago | 1

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Answered
final result depending on the consistency of ones and zeros
out0 = [1111000011110000] out1 = [1111111111111111] convert_to_1_bit=@(vector) mean(vector)>0.5; convert_to_1_bit...

27 days ago | 0

Answered
how to randomly delete number
Your code looks like you want to randomly fill one location with a one, but it has a bias toward the middle. The code below does...

27 days ago | 0

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