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Torsten


1,983 total contributions since 2013

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Answered
Optimisation of parameters in a PDE
https://de.mathworks.com/matlabcentral/answers/406938-fitting-the-numerical-solution-of-a-pde-with-one-parameter-to-some-data ...

4 days ago | 0

Answered
How would I solve a Laplace Equation using the FDM method?
Solve A*V=b where A, b result from the system of equations V(1) = V0 (V(i+1)-2*V(i)+V(i-1))/h^2 = 24*x(i) (i=2,...,Nx) ...

4 days ago | 0

Answered
By what I can replace randint() function.
r = rand(1,1); k = min(floor(10*r),9)+5

4 days ago | 0

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Answered
How to solve this equation?
fun=@(i)400000000*(1+i)^-1+500000000*(1+i)^-2+760000000*(1+i)^-3+200000000*(1+i)^-4+140000000*(1+i)^-5+3105237.5*((1+i)^46-1)/...

4 days ago | 0

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Answered
I want to program (solve this equation for h) this problem in Matlab but I do not know the appropriate function to use.
h can be explicitly solved for: par.Vp = 26.01; m_Lp = 24973; hss =0.96; par.Alpha_Lp_av = pi/180; par.theta = ...

5 days ago | 1

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Answered
Error using pdepe (line 293) Spatial discretization has failed.
Try function Kronstadt_HW4_problem3_pdepe %This is a dimensional formulation close all Nx=201; ...

5 days ago | 2

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Answered
A PDE equation giving meaningless results
Try function main % simple PDE % Equation: dC/dt = K * d^2C/dx^2 - kr * C % IC: C0 = 0.762471166 ...

5 days ago | 0

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Answered
How are initial values chosen for either lsqcurvefit or nlinfit functions?
There must be some mathematical operation within your objective function that gives Inf, NaN or something similar (e.g. division...

5 days ago | 0

Answered
differentiation for a function
syms x y(x) diff(x-y^2,x) Best wishes Torsten.

6 days ago | 0

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how to stop dde23 when one of states reach certain value?
Use the "Events" option of dde23. Best wishes Torsten.

6 days ago | 1

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Answered
How to set open boundary conditions with Pdepe for advection-diffusion-reaction of concentrations?
Choose your interval where you solve your equations big enough. This way, you won't come into trouble with the boundary conditio...

7 days ago | 1

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Answered
simultaneous fitting of two plots with two functions
xdata=[x(:,1); x(:,1)]; ydata=[y1(:,1); y2(:,1)]; fun=@(x,xdata) [f1(xdata(1:numel(xdata)/2),x(1),x(2),x(3),x(4)); f2(x...

7 days ago | 0

Answered
simultaneous fitting of two plots with two functions
Use "lsqcurvefit" with the data set xdata = (x,x),ydata = (y1,y2). Best wishes Torsten.

7 days ago | 0

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Answered
Is it possible to use DuDx as boundary condition in pdepe if DuDx doesn't appear in the equation in a system of PDE/ODE?
Mathematically, an ODE does not need a boundary condition - the value of an ODE in a boundary point is given by solving the ODE ...

7 days ago | 1

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Answered
1st order differential equation , boundary conditions
syms y1(t) y2(t) eqn = [diff(y1,t) == y2*y1*log(450/y1), diff(y2,t) == 0]; cond = [y1(0)==40, y1(15)==95]; [y1Sol(t) ...

10 days ago | 0

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Answered
1st order differential equation
This is a boundary value problem - use "bvp4c" instead of "ode45". Or try "dsolve". Best wishes Torsten.

10 days ago | 0

Answered
Problem of integral combined with fzero
Instead of specifying a point (0.01) in the call to "fzero", you should specify a search interval which excludes the point c0=0....

10 days ago | 0

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Answered
could anyone help me to solve the issue in the following code
X=[3] for t=1:length(X) A = partitions([X(t)]) for d=1:length(A) if length(A{d})>1 for e=1:leng...

11 days ago | 1

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Answered
How can I solve a system of differential equations of second order?
Write your system as w1' = w2 w2' = k*(w4*B3(w1,w3,w5)-w6*B2(w1,w3,w5)) w3' = w4 w4' = k*(w6*B1(w1,w3,w5)-w2*B3(w1...

11 days ago | 0

Answered
CDF and Inverse CDF of Wrapped Cauchy Distribution
function main p = linspace(0,1,11); prob = linspace(0,1,100); x = zeros(numel(p),numel(prob)); for ...

13 days ago | 1

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Answered
matlab pdepe boundary conditions help
"pdepe" is a solver for parabolic/elliptic partial differential equations of 2nd order. Your equations are hyperbolic equations ...

13 days ago | 0

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Multiple parameters optimization having calculated and experimental values
function main P_k = ...; Hcexp = ...; T_k = ...; z = ...; w = ...; v = ...; c = ...; a...

17 days ago | 1

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Answered
How to find the exact solution of heat equation U_t=U_xx bc U(0,t)=0=U(1,t), U(x,0)=sin(pix). Also Matlab code?
Easy: fun = @(x,t)sin(pi*x).*exp(-pi^2*t); x = linspace(0,1,50); t = [0.0 0.1 0.2]; [X,T] = meshgrid(x,t); U = ...

17 days ago | 0

Answered
Create a vector z with 1000 elements generated by the rand-function. The generated values must have a mean value of 0.5 (mean(0.5)). And a standard deviation of sqrt(1/100*12), (std(x)).
0.5*(a+b) = 0.5 1/12*(b-a)^2 = 0.12 Solve for a and b. This will give you the interval [a b] for which you must gener...

17 days ago | 2

Answered
Differential Equation with Coefficients as Integral Functions
fun=@(x,y)[y(2);-y(2)*integral(@(z)z.^2+3*z-1,0,x)]; is a suitable function to be used with ODE45, and it represents your d...

17 days ago | 1

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Answered
calculating sum of an array by using if-or statement in matlab
Deger = [20 25 27 28 31 32 33 34]; Node1 = [1 2 5 6 7 4 3 3]; Node2 = [2 5 6 7 4 3 2 6]; minimum = min(min(Node1),min...

17 days ago | 0

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Answered
how to define an integral function
fun=@(z)z.^2+3*z-1; F=@(x)integral(fun,0,x); F(10)

18 days ago | 1

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Answered
Square of 20 random number sum up to 1
r = r / sqrt(sum(r.^2)) Best wishes Torsten.

18 days ago | 0

Answered
How to fit a curve with negative powers of x
If you want to fit parameters a0,...,an to a function of the form y = a0 + a1*x^(-1) + a2*x^(-2) + ... + an*x^(-n) you c...

18 days ago | 0

Answered
could anyone help me how to write the bell number equation in matlab
nfinal = 10; b(1)=1; for i=2:nfinal+1 b(i)=0.0; for j=0:i-2 b(i)=b(i)+nchoosek(i-2,j)*b(j+1) end ...

19 days ago | 0

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