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# Stephan

##### Last seen: 2 dagar ago
1 116 total contributions since 2017

Knowledge means knowing where it is written...

Interested in:
- Optimization
- Mathematical Modelling
- Improvement of my programming skills

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Sort and accumulate data in a matrix
Here is an example: A = [-10 0 10 10 20 -20 30 -30 40 -50 50 -40 -10 0 0 10 20 -20 30 -30 40 -50 50 -40 40 40 40]; groups = fi...

21 dagar ago | 0

How to save the 60 value in two columns as a csv file?
Use writematrix for this beginning from R2019a. For earlier releases you can use csvwrite. If x and y are of size 60x1 why not ...

21 dagar ago | 0

How can I solve a nonlinear model using Newton Raphson ?
One way: result = fsolve(@fun,[1 1 1]) function F = fun(x) F(1) = x(1) + x(2).^2 + cos(x(3)) - 2; F(2) = x(1) + sin(x(2)) ...

23 dagar ago | 2

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How display a log space bar figure ?
% Set y-axis to log scale set(gca, 'YScale', 'log')

23 dagar ago | 0

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can anyone tell whre is the error ?
x=-2*pi:0.01:2*pi; y=exp(x); z=sqrt(exp(-x)); figure(3) p=plot(x,y,'r',x,z,'b'); p(1).LineWidth = 2; p(2).LineWidth ...

29 dagar ago | 0

How to replace the empty cells in a cell array by a 4-bits string?
load('Key.mat'); Key1 = Key(:); Key1 = reshape(replace(string(char(Key1{:}))," ","0000"),size(Key,1),size(Key,2)); results...

30 dagar ago | 0

How to generate a symmetric Toeplitz matrix?
>> toeplitz([-pi 0 pi]) ans = -3.1416 0 3.1416 0 -3.1416 0 3.1416 0 -3.14...

ungefär en månad ago | 4

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"syms", "sym", and "mupad" functions cause MATLAB to freeze
R2017b had this bug, but it was fixed in update 7 and following. Try to install the latest update for your release - see Step 2:...

ungefär en månad ago | 0

How to use VPA (variable precision arithmetic) in calculating HH band via dwt on an image?
You can not do this. dwt2 accepts only double as input and outputs double. vpa works on symbolic variables and returns a symboli...

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String to Categorical array
x = [zeros(1,120), ones(1,240)]; res = categorical(x, [0, 1], {'Z', 'O'});

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Reducing 2nd order ODE into coupled ODE. Solve using Euler Method and graph.
tspan = [0 5]; % time span to integrate y0 = [3 0]; % initial conditions %Start of Euler Method syms y(t) E = diff(y,2) + ...

How to convert cell array to double?
c = {[1 2],[2 3]} s = cell2mat(c) s = unique(s)

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hi,i am getting error as not enough input arguments,while i run the below code....?? please let me know that?(the error is in second line of code)
Works fine for me, if called with *_2_* input arguments: res = trio(3,4) function x=trio(m,n) x=rand([3*m n]); ...

How to solve coupled (differential) equations of motion using matlab?
Whta is the problem? There is an analytical solution (here assumed that vx0 and vz0 are equal to 1): syms w b g m x(t) y(t) z(t...

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Undefined operator '/' for input arguments of type 'function_handle'
b=400; %mm d=500; %mm Asv = [3000 5000 3000 5000]; %mm^2 fckv = [30 30 90 90]; %Mpa num_fckv = numel(fckv); fsolve_opt...

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Can't plot function
x = linspace(0,10); y = sqrt(1+x.^2)./sqrt(x.^4-x.^2+1); plot(x,y)

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Fit Powerlaw to Data
https://de.mathworks.com/help/curvefit/custom-nonlinear-models.html

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...

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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...

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...

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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...

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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]; ...

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 ...

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...

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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 ...

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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...

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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...

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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...

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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...

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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#...