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Stephan


1,100 total contributions since 2017

Knowledge means knowing where it is written...

Interested in:
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- Improvement of my programming skills

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Answered
Numerical Solution for a System of Three ODEs with Different Constant for Each Time Element
Use interp1 for this. Here is an example: https://de.mathworks.com/matlabcentral/answers/487412-using-ode45-to-solve-differenti...

15 hours ago | 0

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Answered
Text file manipulation, find specific lines, find there a string and replace the specific line with new content
There is a bunch of possibilities to manipulate strings: https://de.mathworks.com/help/matlab/ref/extractafter.html https://de...

15 hours ago | 0

Answered
Fitting an equation to a Sine Function with NonLinearModel.fit
"...I already tried using the "cftool" function in matlab but it did not have the equation I need...." Did you notice that yo...

20 hours ago | 0

Answered
How to replace last 3 digits in a floating point number by another 3 digits
format long x = -3.141592653589793; a = 287; x_new = sprintf('%.15f',x); x_new(end-2:end) = (sprintf('%d',a)); x_new = st...

21 hours ago | 0

Answered
I am trying to use ODE45, but I keep getting an error with myfcn saying I don't have enough inputs?
There are at least 4 problems in your code: 1. Split your main code and your ode function: tspan = [0 10]; f0 = [0 0]; ...

23 hours ago | 1

Answered
Having trouble with ODE45 and a System of Ordinary Differential Equations
For every equation you have to input an initial condition. You have 8 but only give 2 initial conditions to ode45. Also your ...

1 day ago | 0

Answered
Is there a function to turn ?x2 matrix of coordinates of vertices of a polygon into a ?x4 matrix of coordinates of line segments of that polygon?
Yes, circshift will do the job: A = [2, 4; 5, 6; 6, 6; 8,5] B = [2, 4, 5, 6; 5, 6, 6, 6; 6, 6, 8, 5; 8, 5, 2, 4] % The sol...

1 day ago | 0

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Answered
could anyone help me to display the values in the matrix which are greater than the average value for the following code
B, C and D are not needed, if you use the inbuilt function mean: A=[3.3734 5.1245 4.3729 2.8406 6.5283 4.8144 ...

1 day ago | 0

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Answered
How to raise a matrix to multiple powers 0 to 100.
Here is a vectorized solution without using a for loop: % Let A be your matrix result = reshape(A(:).^(1:100),size(A,1),size(A...

1 day ago | 0

Answered
How can calcuate the lines of code efficiently?
Yes, you can if you avoid using a loop and vectorize your code - see here: tic %%%code nx=512; ny=nx; dx=1; dy=dx; format...

1 day ago | 1

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Answered
how can i differentiate a constant in simulink?
You already have done everything exactly correct - Simulink also did what is correct. What is the derivative of y(t)=3 with resp...

2 days ago | 0

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Answered
Eigenvalues and Eigenvectors of Symbolic Matrix
syms E t H = [E -t -t -t -t 0 0 0 0;-t E 0 0 0 -t -t 0 0;-t 0 E 0 0 0 0 -t -t;... -t 0 0 E 0 -t 0 -t 0; -t 0 0 0 E 0 -t 0...

2 days ago | 0

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Answered
what is wrong with my script
clear all for loop_index = 1:2 x = input('Input number to convert'); units = input('Input the units to convert from','s...

2 days ago | 1

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Answered
Any trick to name a variable with decimal number?
No, it is simply not allowed in Matlab. No way, no trick: https://de.mathworks.com/help/matlab/matlab_prog/variable-names.html#...

3 days ago | 0

Answered
PULL OUT A SPECIFIC WORD FROM A LONG STRING
You might want to start reading here: https://de.mathworks.com/help/matlab/matlab_prog/searching-and-replacing.html

3 days ago | 1

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Answered
How do I create a for loop to extract data from table?
No loop is needed: A = unstack(ReactionTime,'RESPONSE_TIME_ehmi','videostring') since you have invalid names for you video fil...

3 days ago | 0

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Answered
complement of an image
I = fliplr(imread('cameraman.tif')); I1 = triu((I),1); I2 = tril(imcomplement(I)); I_res = fliplr(I1+I2); imshow(I_res) B...

3 days ago | 1

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Answered
Trapz gives "Second and third argument must either be variables or a variable and a nonnegative integer specifying the number of differentiations."
syms x f_scalar = @(x) 5*x^2+3*x-4; g_scalar = @(x) -4*x^2+6*x+5; f = @(vec) arrayfun(f_scalar,vec); g = @(vec) arrayfun(g_sca...

3 days ago | 0

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Answered
Problem with input of ode113
I_1= pi^2; I_2= -2*pi^2; params.tau= 10; g= 0; V_1= -65; V_2= -65; state= [V_1;V_2]; I= [I_1;I_2]; options = odeset('ab...

4 days ago | 0

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Answered
How to define discrete variables in GA (genetic algorithm)
https://de.mathworks.com/matlabcentral/answers/401059-setup-discrete-values-for-decision-variables-in-optimization-problems

4 days ago | 0

Answered
Surrogate search with integer parameters
|*intcon*| was introduced to surrogateopt in R2019b. <https://de.mathworks.com/help/gads/release-notes.html>

4 days ago | 0

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Answered
Accessing value in a cell
Edited because of the comments: a = {'1,65,4,5'} b = str2num(a{:}) b(2)

5 days ago | 1

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Answered
Passing parameters in boundary value problem using BVP4C
See here: <https://de.mathworks.com/help/optim/ug/passing-extra-parameters.html |*passing extra parameters*|>. I suggest to eith...

5 days ago | 0

Answered
How to extract frames from a .mp4 video?
outputFolder1=('video'); v1=VideoReader('Clock.mp4'); vid1Frames=read(v1); for frame=1:size(vid1Frames,4) outputBaseFileNa...

5 days ago | 0

Answered
Plot pixels from 2D boolean array
% your array A = randi(2,101)-1; % the result; R=255*ones(101); G=255*(-A+1); B=255*(-A+1); res = cat(3,R,G,B); ...

5 days ago | 0

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Answered
Return a value from a table
Quarter = {'Q12019'; 'Q22019'; 'Q32019'; 'Q42019'; 'Q12020'; 'Q22020'; 'Q32020'; 'Q42020'}; QuarterStartDate = ['2019-01-01'; '...

6 days ago | 1

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Answered
Inserting vertical and horizontal line in bodeplot
xline and yline should work for this purpose. Both functions were introduced with R2018b. If you use an earlier release, just de...

6 days ago | 1

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Answered
Solving EOM coupled equations using ode45
syms x(t) y(t) eq(1)=diff(y,t,2)==(3/2)*(9.81*sin(y)-diff(x,t,2)*cos(y)); eq(2)=11*diff(x,t,2)+(1/2)*cos(y)*diff(y,t,2)-(1/2...

6 days ago | 1

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Answered
Array indices must be positive integers or logical values. Error in (line 8) mr(t)=mi-((mi-mf)*(t./tb));
I doubt you want t to have only one point. Also no for loop is needed: mi=2290000; mf=130000; tb=165; t=linspace(6.5,165...

6 days ago | 1

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Answered
could anyone help me how to combine data in two columns
Res = [A B]

7 days ago | 0

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