Torsten

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Can I specify different thermal conductivities for different regions in a space using Matlap PDE Toolbox? For example, the space is divided into a thermal conductivity space o
There are two ways: A good method is to generate the geometry such that it consists of a certain number of zones to which you c...

etwa 5 Stunden vor | 0

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Finding x and y values of minimum z in 2-variable function.
z = @(x,y)(x.^2).*(y.^3)-1.4*(x.^2).*(y.^2)-3.91*(x.^2).*y+5.78*(x.^2)-... 11*x.*(y.^3)+15.4*x.*(y.^2)+43.01*x.*y-63....

etwa 7 Stunden vor | 0

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Find best fit curve from multiple curves of different size
I parametrized the curves by normalized arc length. To compute the average curve, I took the mean of R- and Z-coordinates of the...

ein Tag vor | 0

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How can I get splines subject to constraints?
This code looks helpful for your purpose: https://uk.mathworks.com/matlabcentral/fileexchange/7976-random-number-from-empirical...

ein Tag vor | 0

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How do I edit a loop to be able to store the variables and outputs used in each loop in a way which can be graphed?
Be careful here. In correlations for friction factors, log is usually meant as log to the basis of 10, not the natural logarithm...

3 Tage vor | 0

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Question solve(eqn)
Replace solve (f1, f2, f3, f4, f5, f6) by [a0,a1,a2,a3,a4,a5] = solve (f1, f2, f3, f4, f5, f6) But note that extrapolating t...

3 Tage vor | 0

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find is not working in a loop, it skips numbers
Never test two double precision numbers for equality. Because of floating point arithmetic, they will almost always be classifie...

3 Tage vor | 0

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Can someone rectify this code?
My guess is that you work with an older MATLAB version where script and function parts cannot be mixed. Thus save function F =...

4 Tage vor | 0

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elseif that goes through previous statements but with different parameters
if e(t)==1 nn1 = nn11; nn2 = nn21; elseif e(t)==2 nn1 = nn12; nn2 = nn22; elseif e(t)==3 nn1 = nn13; nn2 = nn23...

5 Tage vor | 0

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syms to another .m file
Call the other .m-file with the syms-equation (or function) as input argument. syms x f = x.^2; result = fun(f) function res...

5 Tage vor | 0

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Clarification regarding Sensitivity Analysis of a coupled ODE system using the odesensitivity function
Start with the simple example y'(t) = p(1)*y(t), y(0) = 1. The solution is y(t) = exp(p(1)*t). The (local) sensitivity is ...

5 Tage vor | 0

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How to make ode45 store/return only results of every n-th time step to reduce memory use?
You can specify the times when the solution should be saved in the input variable "tspan" to "ode45". And you should test wheth...

6 Tage vor | 1

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Energy Harvesting of Cantilever Beam with MSMA alloy1
I inserted "warning('off')" at the start of your code because your matrix M in your function "system_eqs" is singular and MATLAB...

8 Tage vor | 0

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Sampling from inverse gamma distribution by specifing mean and standard deviation
It works for mu = 0.5, sig = 0.5, e.g. . It seems that your distribution parameter "a" is too close to the critical value of a =...

10 Tage vor | 0

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How to code an equation with that integrates a vector.
If there is no closed-form expression for u (e.g. if u depends on x), you can solve the vector-differential equation dx/dt = u ...

11 Tage vor | 0

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The surface area won't round to one decimal place and I don't know how to get rid of the 'e's.
https://uk.mathworks.com/help/matlab/ref/fprintf.html https://uk.mathworks.com/help/matlab/ref/format.html

11 Tage vor | 1

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Need to correct the following script in part of Infinitely Long Horizontal Cylinder (to be of perfect circular base)
%% 2. Infinitely Long Horizontal Cylinder subplot(1,3,2); theta = linspace(0, 2*pi, 30); x_v = linspace(-10, 0, 20); [Theta,...

18 Tage vor | 0

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Grey box model of 1d heat diffusion in a rod (official mathworks example)
I think it will be simpler to couple "pdepe" for the solution of your PDE and "lsqnonlin" for optimizing your model parameters. ...

18 Tage vor | 0

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trouble using pdepe to solve system of pdes
Your initial condition for u(2) at x = 0 is not consistent with your boundary condition. Use function u0 = icfun(x) global ...

18 Tage vor | 0

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How plot 2d of more than 3 function and substitute the number in each function separate parameter?
y=@(x,t,m)real(((-0.385e1 .* tanh(-x - 0.310e1) - 0.385e1 * coth(-x - 0.310e1)) .^ (0.1e1 ./ m ./ 0.2e1)) .* exp(i * (0.431e1 * ...

20 Tage vor | 1

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Help with the Deflection of a Plate in MATLAB
You are trying to solve the heat conduction equation with a homogeneous heat sink -q/D and boundary temperature 0. Is this the s...

21 Tage vor | 0

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Time dependent variable in plot.
The simplest method is to define x, compute y in a loop and plot: x = 0:0.1:15; for i = 1:numel(x) if x(i) >= 0 & x(i) < ...

22 Tage vor | 1

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Solving Advection Equation PDE with 2nd order Accuracy
Usual second-order schemes for the advection equation will always produce oscillations. Section 3.1.3 of the enclosed article su...

22 Tage vor | 0

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How can I use fmincon with general (user defined) nonlinear constraints?
g = @(x)deal([gl(x(1:nx),x(nx+1:nx+ny));gf(x(1:nx),x(nx+1:nx+ny))],[])

23 Tage vor | 0

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Assign fitlme output to a variable
See https://uk.mathworks.com/help/stats/linearmixedmodel.html The functions that can be applied to a fitlme object are: a...

23 Tage vor | 0

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Avoiding -0.0000 as an output
The results for d2,...,d4 aren't exactly 0 because of floating point errors in their computation. So without artificially manipu...

24 Tage vor | 0

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solve symbolic eigenvalue problem
If you want an analytical expression for the eigenvalues dependent on the parameter a, your matrix A must have dimension <= 4. ...

24 Tage vor | 0

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problem to solve incorrrect
%% R-RRR clear all; clc; close all % Input data AB=0.325; %(m) BC=0.938; %(m) CD=0.675; %(m) CE=0.6; %(m) xD=0.8; %(m) y...

27 Tage vor | 0

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Monte Carlo integration (hit or miss) to find the area of a circle of radius R
You compare the area of the square with side length R and corner points (0,0), (R,0), (R,R) and (0,R) with the area of the quart...

27 Tage vor | 0

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Finding parameters by fitting data to a system of ODEs with lsqnonlin
syms T1(t) T0(t) s d g eqn1 = diff(T0,t) == s - (d+g) *T0 ; eqn2 = diff(T1,t) == 2*d*T0 + (d-g)*T1; sol = dsolve([eqn1,eqn2])...

28 Tage vor | 1

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