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Torsten


Last seen: Today Actif depuis 2013

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How can I evaluate the transition matrix using the fourth order Runge-Kutta ODEs
If it's still of interest: this code seems to work correctly. I don't know why using n = size(A,1); E = A(t+dt/2)*(eye(n)+dt/2...

environ 16 heures il y a | 0

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Why do I receive error using BVP5C "The boundary condition function BCFUN should return a column vector of length 1"?
You have one first-order ODE, but two boundary conditions. That's mathematically impossible - you can impose only one condition....

3 jours il y a | 0

| A accepté

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Event function and ODE.
Don't use both events simultaneously in your event function. Start the solver with the first event function and integrate until...

3 jours il y a | 0

| A accepté

Réponse apportée
Trouble solving system of pdes with pdepe
"pdepe" is a solver for parabolic-elliptic partial differential equations. The positions with zero elements in the f-vector indi...

4 jours il y a | 0

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Solving the differential equation gives unexpected results. How to fix that?
Better ? v(t) = v(0) - g*t - v0*log(m0/(m0-k*t))

6 jours il y a | 0

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Define function for transient transient boundary condition
F1= 3.843e-8; F2= -3.482e-5; F3= 1.179e-2; F4= -1.95; F5= 23.69; Trefrig = @(location,state)F1*state.time^4 + F2*state.time...

7 jours il y a | 0

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How to write an event function to stop at second or third x axis crossing.
I'd make the solver stop at each x-crossing. After it returns control to the calling program, add 1 to the number of crossings a...

8 jours il y a | 0

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Why don't I need a comment character after an (...) ellipsis?
Most probably there is the convention that ... is the symbol to connect two subsequent lines and that everything behind the ... ...

8 jours il y a | 1

Réponse apportée
AYUDA EN CODIGO DE MATLAB PARA UN ESTRUCTURA DE PUNETE EN 3D
If you insert the lines % Calcular desplazamientos en los grados de libertad libres rank(K_aa) size(K_aa) before the command...

9 jours il y a | 0

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Why Is Colon Operator Not Equivalent To linspace Command?
Both arrays seem to be generated differently such that floating point issues come into play: z1 = 0:.08:50000; z2 = linspace(0...

9 jours il y a | 0

Réponse apportée
How to draw the function relationship graph between two or three variables, where these variables are solved by a system of equations.
Here are the three possible solutions for VL given tc. % 定义符号变量 VL=20; syms tc t2 Q_out Vco Vcn VL %参数关系 L=100e-9; C=50e-6...

9 jours il y a | 0

Réponse apportée
Plotting a variable versus space and time
Use "slice": https://uk.mathworks.com/help/matlab/ref/slice.html

9 jours il y a | 0

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checkGradients, but the objective function has two inputs: x and xdata?
valid = checkGradients(@(p)semiCircle(p, Q),p0)

9 jours il y a | 0

| A accepté

Réponse apportée
How can I evaluate the transition matrix using the fourth order Runge-Kutta ODEs
Seems to work. What's your problem ? Don't use the transition matrix to integrate in one pass. If you have to, generate it with...

9 jours il y a | 0

Réponse apportée
problem with vpa and symsum
The numerical bessel functions are not able to compute your sum correctly (for higher values of k, they return NaN) (see below)....

10 jours il y a | 0

| A accepté

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getting singular jacobian error while using bvp4c solver
I can't interprete your solution curves, but it seems to be a problem for the solver that the Scaled Mass goes to 0 with increas...

11 jours il y a | 0

Réponse apportée
Empty sym: 0-by-1 : Don't understand why
I multiplied by the denominators and squared to get rid of the square roots. Your system seems to have 4 (complex-valued) solut...

12 jours il y a | 0

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Réponse apportée
Non-linear least squares estimation with linear constraints in Simulink?
I vaguely remember that using "lsqcurvefit" within Simulink requires to use the Levenberg-Marquardt algorithm. I can't answer wh...

12 jours il y a | 1

| A accepté

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Do I have a convergence issue?
B0 = 0.5; B = fsolve(@fun,B0) function residual = fun(B) g = 10; %m/s^2 Q = 70*1000; %N/m tau_L1 = 24*1000; %Pa t_w = 30...

12 jours il y a | 0

Réponse apportée
HOw to find displacement integrating velocity?
The equation from above describes the stationary velocity profile over the length L. Thus replacing v by dx/dt does not make sen...

13 jours il y a | 1

| A accepté

Réponse apportée
Integration symbiolic form in matlab gives error
I think you will have big problems if you try to integrate a function with values in the order of +/- 1e70. syms r theta Part_...

16 jours il y a | 0

Réponse apportée
Why the symbolic method fail when I tried to expand a ellipse
I get the correct result (at least for coe = [1;1;1;1;1;1]) : aex = expandA(ones(6,1)).' function aex = expandA(coe) A = co...

16 jours il y a | 0

Réponse apportée
Why did i receive error with my for loop ode45 function?
I used numerical values for L1, L2, mblade, kt and Jblade right from the beginning and got expressions for dL_dtheta2_numeric an...

18 jours il y a | 0

Réponse apportée
Why do i get the error (Array indices must be positive integers or logical values) when trying to calculate the determinant
I don't get any error. But you shouldn't overwrite the function "det" by using the variable name "det" for the result. Name it ...

19 jours il y a | 0

Réponse apportée
having if/else statement go to previous input
r = rand(); if opt == 1 || (opt == 3 && r < 0.5) abc else xyz end

22 jours il y a | 0

Réponse apportée
6x6 system of multivariate quadratic equations ... non-negative real solutions
I think there is no specialized solver for a system of quadratic equations. Thus a general nonlinear solver ("fsolve","lsqnonlin...

22 jours il y a | 0

Réponse apportée
Color Burr distribution function line
pd = makedist('Burr','alpha',1,'c',2,'k',5); R = random(pd,100,1); pd = fitdist(R,'Burr'); figure(1) plot(pd) x = 0:0.01:2;...

22 jours il y a | 0

| A accepté

Réponse apportée
Writing ODE equations for ode45 to solve;
The form of the equations that can be solved by ode45 is M*y'(t) = f(t,y). So you can decide whether you choose M to be the iden...

24 jours il y a | 0

| A accepté

Réponse apportée
How to use a solver to get the terminal velocity of a sphere.
v0 = fsolve(@fun,1) function res = fun(v0) d_p =...; rho_air = ...; nu_air = ...; rho_w = ...; g = ...; Re ...

25 jours il y a | 1

| A accepté

Réponse apportée
Nusselt number and skin friction for bvp4c
Nu1 = -(1+bk*(1+m))*S1.y(5,1) Nu2 = -(1+bk)*S1.y(5,end) Tau1 = (1-bv*(1+m))*S1.y(4,1) Tau2 = (1-bv)*S1.y(4,end)

25 jours il y a | 0

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