# Torsten

Last seen: Today Active since 2013

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use of pdepe for a space-dependent diffusivity
First: Don't name the vector "diff" since "diff" is an internal MATLAB function. Name it D, e.g. Second: To get the correct val...

ungefär 3 timmar ago | 0

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If I have an array and I need to find an element in the array how do I go about it?
Compute 100*states(:,1)+10*states(:,2)+states(:,3) and use "find" to compare with C.

ungefär 22 timmar ago | 1

Solve a differential equation and determine when it gets close to steady state
You can use an event function for the ODE integrator and stop integration when abs(dy/dt) (in your case abs(0.1 * (c-20) * (23-c...

ungefär 23 timmar ago | 0

the degradation of ozone in aqueous solutions (water). When I plot the all three components, the plot stays at the 0 value for all components.
There seems to be a singularity in the solution at t approximately 320. ProjectOzone() function ProjectOzone clc ki = 7e-3;...

en dag ago | 0

The code below runs nonstop, and the results are not shown. why is that?
The code below runs nonstop, and the results are not shown. why is that? "solve" won't succeed for your system of equations bec...

3 dagar ago | 0

Create number of for loops depending on size of N
The N columns of the resulting C-matrix contain i_first, i_second,... imax = 8; N = 4; i_average = (sum(0:N-1)/N+sum(imax:-1:...

3 dagar ago | 0

How to make Matlab recognize that an expression rewritten by using subexpr() is equal to the original expression?
You have to resubstitute sigma by (a+b+c+d+e)^(1/2) in x_2 to compare with x: syms a b c d e f x x = a + (a+b+c+d+e)^(1/2) + c...

3 dagar ago | 0

plot the output c(t) using mathlab and show setting time on you graphf
Use "fplot" as done in your code above.

3 dagar ago | 0

Describe the solution trajectory of differential systems with mixed time-varying delay
To write your equations as a system of delay differential equations that can be handled by a MATLAB solver, set x3 = integral_{...

3 dagar ago | 1

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Plot between Nu vs Ra
Replace Ra_values = 10:100:100000; by Ra_values = (10:100:100000).';

3 dagar ago | 0

Resetting only a section of my state during event driven ode45 simulation
After the event has been triggered, control is returned to the calling program. If you want to continue integration with the e...

4 dagar ago | 1

Index exceeds the number of array elements. Index must not exceed 1.
path_length_BS_IRS_reflect_UE(i) does not exist for i > 1 because path_length_BS_IRS_reflect_UE is a scalar value, namely 223.60...

4 dagar ago | 0

Dot indexing is not supported for variables of this type.
Test before your loop % Loop through each entry in the list and extract data for i = 1:numEntries dt(i) = dateti...

4 dagar ago | 0

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How do I know what method Matlab is using when plotting ltiview?
I don't know Itiview nor risetime, but isn't there a literature link in the documentation for the function you are using ? If ...

4 dagar ago | 0

How to solve algebraic equations for different values of variables ?
% Solve the equation eqn = Ac.*I.*eta-m.*c.*(Te-Ti)==0 for i=1:numel(eqn) s = solve(eqn(i),Te); S(i) = vpa(s(s>=0)); en...

5 dagar ago | 0

function file used with 2 Matrices as input
You are not allowed to use the same name for the function and an output array. Thus rename one of them. And ln_AOU as output pa...

6 dagar ago | 0

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Solving a linear programming problem uising linprog
A = -[110 205 160 160 420 260;... 4 32 13 8 4 14;... 2 12 54 285 22 80]; b = -[2000; 55; 800]; Aeq = []; beq = ...

6 dagar ago | 1

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BVP Error, help with explaination
The solver is no longer able to capture the steep gradient of your solution at x=0. Look at sol.x in the last step of the cont...

6 dagar ago | 0

Data type symfun (code problem)
If your MATLAB release throws an error (R2024a does not as you can see above), try [n(x) d(x)] = numden(df(x)) instead of [n ...

7 dagar ago | 1

The estimation error is strangely obtained from Simpson's 1/3 rule...
syms a b c d e real syms t real f(t) = a*t^5 + b*t^4 + c*t^3 + d*t^2 + e*t; s = 0; i = -1/2; while i < 959.5 i = i + ...

7 dagar ago | 0

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V2H Optimization: No feasible solution found
Use energyStorage = optimconstr(T); energyStorage(1) = BSS_SOC(1) == 0; energyStorage(2:T) = BSS_SOC(2:T) == BSS_SOC(1:T-1) -...

8 dagar ago | 1

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Need to solve the following equation with three knowns and 2 unknowns.
H_BM = rand(100,1); g_mean = rand(100,1); Wi = rand(100,1); Hi = H_BM; gi = g_mean; x = Hi.*gi; y = Wi + Hi.*gi; fitl...

8 dagar ago | 1

Why does Matlab not recognize fieldnames function?
You overwrite the "fieldnames" function by setting it to a variable value: fieldnames = fieldnames(results.digitalMap);

9 dagar ago | 0

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Simulate Fick's 1st and 2nd laws of mass diffusion.
The correct update for inner grid points is C_new(i,j) = C_old(i,j) + dt * (D_x*(C_old(i-1,j)-2*C_old(i,j)+C_old(i+1,j))/dx^2 +...

10 dagar ago | 0

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Indices shown in plot are off
My guess is that the x-axis has a resolution of 10.

12 dagar ago | 0

issue in calculation of wave speed
The below code will at least give you the correct update of the solution. You don't initialize "half_max_positions" ; that's wh...

12 dagar ago | 0

Minimize difference between two data sets
Use [output] = [method](@(AB) my_func(AB(1),AB(2)), [A B]) instead of [output] = [method](@(A,B) my_func(A,B), [A B])

12 dagar ago | 0

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You mean something like this ? X = linspace(0, 1, 100); W = linspace(0, 2, 30); m = 0; sol = pdepe(m, @pdefun, @ic, @bc, X, ...

12 dagar ago | 0

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