Jan

Last seen: 3 days ago | Active since 2009

It is easier to solve a problem than to guess, what the problem is.

Questions about FileExchange submissions are welcome - get my address from the code. I do not answer mails concerning questions in the forum.

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Why does my graph come out wrong?
fplot(@(x) ((x.^2)-1).^(2/3))

3 days ago | 0

Answered
BUTTER function returning slightly different results for Signal Processing Toolbox in R2020b and R2021a on same computer (Win10)
You can compare both results with this cheap implementation of a high pass Butterworth filter: format long g [num, den] = bu...

7 days ago | 0

Answered
My implemetation for Newton's method doesn't seem to be working
I've cleanup the code, e.g. removed the not needed "x_old". Avoid using the names of important Matlab functions as variables: ep...

7 days ago | 0

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Answered
Get plot lines title in a GUI plot by mouse click on each line
You can define a ButtonDownFcn for the lines: LineH(1) = plot(1:10, rand(1, 10), 'r', 'DisplayName', 'Line 1'); LineH(2) = plo...

12 days ago | 0

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Answered
Error on using ODE45 and cannot prompt output
I get a different error message, which is very clear: k=1e9; r = 4.31e-3; kt=0.9; D=1; timespan=[0 30]'; C0=40000; first=...

12 days ago | 0

Answered
Looping over an array using Fibonacci numbers as a range to calculate the mean
What should happen with the last chunk, if you cannot find enough elements in the input data? Should the 1st term really be: me...

13 days ago | 0

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Answered
Complexity comparison: remove a key-value pair from a containers.map vs removing an item from an array.
You can run a short test: function [] = MapTest figure; len = 1e3:5e4:1e6; tMap = zeros(1, numel(len)); for idx = 1:nu...

13 days ago | 1

Answered
How can I obtain the T and Y for R Runge Kutta method?
Store the first version starting with "function R=rk4(f,a,b,ya,M)" in a file called "rk4.m" and save it to a folder, which is i...

14 days ago | 0

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Answered
Gurobi mex file cannot be found despite it being clearly there
Use the Dependency Walker to find out, which library is missing: https://www.mathworks.com/matlabcentral/answers/95906-how-do-i...

14 days ago | 0

Answered
find the equal values that stand together on the same row or column or diagonal in the matrix
Maybe you mean: pool = [-1, 1, 2]; index = randi([1, 3], 15, 15); data = pool(index); match = conv2(data > 0, ones(3, 3)...

14 days ago | 1

Answered
Index in position 2 exceeds array bounds (must not exceed 1).
dx1dt = x4 .* cos(x5) .* cos(u3); % Now dx1dt is a scalar ... x(1,i) = x(1,i-1) + h * dx1dt(1,i-1); % This treats dx1dt ...

14 days ago | 0

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Answered
Storing values from a for loop
B = 1000; R2 = zeros(1, B); % Pre-allocation for iter = 1:B ... R2(iter) = 1 - sse / sst; end A problem is, that R...

14 days ago | 0

Answered
Newton's method - problems in calculating alpha value
In the lines: func = @(x) eps * c_s * x^4 + (alpha_k + 1/(s1/lamda1+s2/lamda2)) * x - ... ((1/(s1/lamda1+s2/lamda2...

19 days ago | 0

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Answered
how to declear global "import java.awt.Robot" and "import java.awt.event.*"?
If such a global import is possible, it might destroy Matlab's stability. The imported functions without wildcards have a higher...

19 days ago | 0

Answered
Performance of log() is wildly different in two different contexts and machines for same data?
Summary: On the 16 GB M1 MacBook, the lines tic tdg_log = log(tdg); toc displays, that the processing needs 1.5 seconds. U...

20 days ago | 0

Answered
Numerical integration of discrete data using higher precision
You explain, that you have discrete data, but the code you show uses a function. If the data are given in double precision, usin...

20 days ago | 0

Answered
Passing multiple Arrays to loop a Function and creating a 1 column array
The code contains some strange details: A = ArrayA; (1,000x1) Double Please use the standard notation. I assume this would be ...

24 days ago | 0

Answered
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
Let Matlab stop at the error using the debugger: dbstop if error Then run the code again. If it stops, chek the sizes of the u...

24 days ago | 0

Answered
how do I put waitbar inside a figure (Matlab 2016a)?
You find a lot of examples in the FileExange. Search there for "porgressbar": https://www.mathworks.com/matlabcentral/fileexcha...

24 days ago | 0

Answered
Calculationg with quternions Matlab function did not work
function p_A = q_transform_coordinate_vector(R_A_B, p_B) % ^^^^^ p_A = q_A_B * q_pu...

24 days ago | 1

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Answered
Error using reshape: Size arguments must be real integers. Except all values are positive whole numbers?
Change: raw_data.variable_mat = raw_data.variable_mat(:,1:reshape_val); to raw_data.variable_mat = raw_data.variable_mat(:,1:...

26 days ago | 1

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Answered
How to solve this error: =: nonconformant arguments (op1 is 1x1, op2 is 100x1)?
T = linspace(0, 10)'; % Time f = 0.1; % Frequency Am = 10; % Phase F = Am*sin(2*pi*f*T); % Sin wave input Now F is a [100, ...

26 days ago | 0

Answered
Can I hit the "OK" button on inputdlg through coding?
See this example for creating your own dialog with a timer: https://www.mathworks.com/matlabcentral/fileexchange/24871-autowarnd...

26 days ago | 0

Answered
Interpolation method of IMAGE
x = zeros(640, 480, 3); x(:, 1:2:end, :) = 1; image(x) This looks confusing to me in the online version: Where are the steps ...

26 days ago | 0

Answered
MEX-file efficiency with multiple file-pass function calls in .m script
Do you use the terms "function" and "script" correctly? Functions and scripts are stored in .m-files. Functions start with the ...

28 days ago | 0

Question

Submit button not working sometimes
A few weeks ago the Submit button in this forum stopped to work for me in about 50% of the cases. Then I copy my answer or comme...

28 days ago | 2 answers | 2

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Answered
Linear indexing in 3D matrix
Look into the code of sub2ind. It is easy to create an inline version of what you want: s = [2, 3, 4]; x = reshape(1:prod(s), ...

28 days ago | 0

Answered
I am facing problem regarding storage of values for d() using for loop which is of 100x100 size for each iteration of a and k.
You overwrite the data by zeros repeatedly: for t=1:L for v=1:elements for w=1:elements % Here all f...

30 days ago | 0

Answered
removing zeros from matrix
x(x==0) = []; % Or: x = x(x~=0); Where do the zeros come from? Instead of removing them it might be easier to avoid to crea...

30 days ago | 0

Answered
Trisurf : How to interactively change the plot opacity?
GUIs are not hard to control. function testGUI % Some test data: [x,y] = meshgrid(1:15, 1:15); tri = delaunay(x,y); z = pea...

30 days ago | 0

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