# Torsten

Last seen: Today Actif depuis 2013

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help solving for Delx
qf = 38.6; T1 = 25; e=0.95; s=5.67e-8; K=300; t=0.12; w=3; fun = @(T,delx) [T(1)-T1; qf - K*w*t/delx*(T(1)-T(2)) - 2...

environ 18 heures il y a | 0

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problem doing implicit plotting
Remove the dot at the end of the expression x.*y.

environ 18 heures il y a | 1

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Why i am getting blank graph? Can someone help me to figure out error in my code.
is_exam3() function is_exam3 L=0.01; M=0; q=0.5; a=0.03; Pr=0.1; b=0.2; p=0.1; m=0.1; e=1.0; H=0.1; E=0.1; o=0...

environ 22 heures il y a | 0

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How to solve the following PDE equation
I think you mean x(s,0) = 10 instead of x(s,t) = 10, don't you ? The easiest way to solve the equation is to discretize the exp...

environ 23 heures il y a | 0

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Matrix is singular to working precision.
Obviously, your matrix is the zero matrix. Most probably the reason is that you don't assign values to K in the loop K(2*cnt-1...

1 jour il y a | 0

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Solving unknown matrics to the power 20
p = [1 0 0 0 0 0 0]; R = [9; 8; 7; 6; 5; 4; 3]; CR = [0.45]; n = 20; TPM = diag([(CR/(p(1)*R(1)))^(1/n),zeros(1,6)]); p*TPM...

3 jours il y a | 0

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Error using pdepe: Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative
"pdepe" is a solver for parabolic-elliptic equations. Thus all equations should have a second-order derivative term in space and...

3 jours il y a | 0

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In matlab, although my matrix is ​​full rank, the solution is still incorrect.Ax=b,A(10000*10000),x、b(10000*1)
The condition number of your matrix D is around 1e11 (see above). This is near to singular. I think you cannot expect a better r...

3 jours il y a | 1

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Too many input arguments error
Your function xa and xn have three inputs (n,x,g), not two (n,g). Thus x_func = @(n, g) (xa(n, g)/xn(n, g))^(1/3); % Example T...

3 jours il y a | 0

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solving symbolic equations with partial derivatives
syms Cf(zf,zr) cf(z,theta) L zref = zf; thetaref = (zf - zr)/L; dCfdzf = diff(cf,z) * diff(zref,zf) + diff(cf,theta)*diff(the...

3 jours il y a | 0

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Calculations with distributions of variables only
Look up "Monte-Carlo-Simulation".

4 jours il y a | 0

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Time-dependent dynamic problem with nonlinear stiffness using ode45
You solve for U and Udot - thus you get values for U and Udot from ode45. Simply compute the matrix K(U) with these values and p...

5 jours il y a | 0

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Error: Data must be numeric, datetime, duration, categorical, or an array convertible to double.
% Declaring Theta and Phi Variables theta = 0:0.1:pi/2; % Phi Values phi_E_Plane = 0; phi_H_Plane = pi/2; % Declaring x...

5 jours il y a | 0

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How to solve this differential equation? I got ''Warning: Unable to find symbolic solution.'' error. What am I missing ?
You don't miss anything - your equation is just too complicated to have an analytical solution. You will have to use a numerica...

7 jours il y a | 0

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fsolve error: Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
Include the line size((2.*x_SW(2).*dfreq_SW_vr.*w(1).*g2) + ((1./4).*x_SW(1).*nu).*(f1b.*zet_0_0 + f2b.*eta_0_0).*g1.*cos(gamm...

7 jours il y a | 0

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Hi All. Just wondering why answer to (i) is not 4.9e+4. an why answer to (iii) is not (9x)/2 or 4.5 x. Many thanks. Brian
For (iii), use syms x real instead of syms x

8 jours il y a | 1

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Overwriting the maximum function evaluation
You didn't include the structure "optim_lsq" in the call to lsqcurvefit.

9 jours il y a | 0

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Operands to the logical AND (&&) and OR (||) operators must be convertible to logical scalar values. Use the ANY or ALL functions to reduce operands to logical scalar values.
if all(abs(grad_g1_val) < tol) && subs(g1, {x1, x2, x3}, x') <= 0 activeSet = [activeSet, 1]; % Constraint 1 is ac...

9 jours il y a | 0

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ODE45 and dsolve result difference
dydx(2)=2-2*y(2)-8*x; instead of dydx(2)=2-2*y(2)-8*y(1);

9 jours il y a | 1

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Intersection condition between two ellipses
I'm surprised that we get a division by zero by the below solution method if the aspect ratio of the two ellipses is equal. Bu...

9 jours il y a | 0

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Arrayfun with Extra Parameters
Test3 = arrayfun(f,a,b) instead of Test3 = arrayfun(@f,a,b)

9 jours il y a | 0

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Extract the indices based on the minimum absolute value
Maybe you mean %define the number of random numbers n = 10; %define the min and max ranges of random values stvar = [0 4]...

10 jours il y a | 0

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How to fit a distribution whose parameters depend on other parameters?
In this case, you must assume a parametric expression for T(z) as well (e.g. T(z) = a + b*z) and add a and b to the parameters t...

10 jours il y a | 0

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Solve and plot system in x and y with varying constants e and t
basically i would like to obtain on the same graph different curves in x and y for a fixed number of combinations of e and t. I...

12 jours il y a | 0

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sol2 = bvp4c(@bvpexam2, @bcexam2, sol);
Ibrardual() function Ibrardual Nt=0.5; Nb=0.5; Le=2; Pr=1; Alpha=[-0.2138;-0.4]; s=1; A=1; %% solution in structure form %...

12 jours il y a | 0

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What is the most computationally efficient factorization of a matrix A?
Prove that the matrix is positive definite and count the number of FLOPs of Cholesky compared to the other factorizations. Sect...

13 jours il y a | 0

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what is the error here?
The error is that the parameter "S" is not an input to function "odeBVP" and thus undefined in f =[y(2);y(3);(1/3)*D1*((y(2)^2...

13 jours il y a | 0

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Runge kutta giving complex numbers
It doesn't make sense to use such discontinuous input data for the solution of a differential equation. Solving a differential ...

16 jours il y a | 0

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How does Matlabs Symbolic Math Toolbox always finds an analytical eigendecomposition for arbitrary polynomial matrices?
For me this begs the question, is the eigenvalue polynomial from eig(...) truly analytic? What do you mean for a polynomial to ...

16 jours il y a | 1

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