Torsten

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Diffusion equation in Cartesian and Cylindrical coordinates
If m = 1, the condition at r = 0 set by "pdepe" is pl = 0, ql = 1. All other conditions make no sense mathematically because the...

1 day ago | 0

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Weighted regression without priority zone, but with finding the minimum possible value for all the differences
x = [1 2 3 4 5 10 20 50].'; y = [5 10 15 20 25 30 40 50 60 90]; z = [265.110074796797 195.008035083193 156.258229529605 129.74...

4 days ago | 1

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Code Matlab for a function that depends in a real parameter
integrand = @(f,y)y.*sin(f(y)); F_alpha = @(f,alpha,x)alpha.*x.*integral(@(y)integrand(f,y),0,1); f = @(u)u.^2; alpha = 1; x...

4 days ago | 0

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Weighted regression without priority zone, but with finding the minimum possible value for all the differences
Use "fminimax". It minimizes the maximum error and is the nonlinear equivalent to minimizing the Inf-norm in linear regression p...

5 days ago | 2

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Why am I getting error using assignin and syms while solving pde using pdepe
Here is the code for the dimensional model. It should be no problem to rewrite it in the non-dimensional form. Note that the s...

5 days ago | 0

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Why am I getting error using assignin and syms while solving pde using pdepe
tau is a vector of values in your code: tau = linspace(0, tau_end, 100); % Non-dimensional time You can't use it as a symbolic...

6 days ago | 0

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Andrica's Conjecture
Use nthprime(1:n+1) to generate the vector of the first n+1 prime numbers. The rest should be simple.

6 days ago | 0

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Forward, Reverse finite difference question
x = 0:0.1:1; f = @(x)x.^2; derf = (f(x(2:end))-f(x(1:end-1)))/0.1; hold on plot(x(2:end),derf); % backward plot(x(1:end-...

6 days ago | 1

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Time interation error while trying to solve a partial differential equation which describes pore diffusion resistance combined with with surface kinetics.
One error, one problem: The error: qr = De; must be replaced by qr = 1; because the boundary condition is given by p+q*f =...

7 days ago | 0

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Numerical differentiation and integration
t = [0,5:10:115]; s = [0, 4892.3, 14041.3, 22371.3, 29926.1, 36764.4, 42965.4, 48634.8, 53910.3, 58961.8, 63981.6, 69165.5, 74...

9 days ago | 0

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error in runge kutta -Unable to perform assignment because the left and right sides have a different number of elements.
You always have to use the variables at the ith time step, not the complete array in the assignments. I didn't check your compl...

9 days ago | 0

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How to plot the temperature unit which is small circle raised at the left of C upper case?
Maybe by adding the interpreter ? In R2024b, your title is correctly plotted without any modifications. x=0:0.1:1; y=x.^2; pl...

10 days ago | 0

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The method of how to calculate the FWHM.
xmax = 0; ymax = 4; x = xmax:0.01:3; f = -x.^2 + ymax; FWHM = 2*interp1(f,x,ymax/2) Or directly use the inverse function of...

10 days ago | 0

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How to make my code run faster
Maybe your system does not have a solution. sol = fsolve(@fun,[1 1 0.1]); fun(sol) sol = 1./sol function equations = fun(par...

10 days ago | 0

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Finding more than one root for nonlinear equation
Equations (5) and (6) are two linear equations in q_t, beta and q_dot_b. Use them to express q_t and beta as linear functions o...

11 days ago | 0

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How would I Solve this System of Trigonometric Equations for Inverse Kinematics?
Solve eqn2 for t1 Insert the result for t1 in eqn1 and solve for t2 Insert the result for t2 in eqn3 and solve for d1

12 days ago | 0

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How to convert a fourth-order ordinary differential equation into a system of first-order ordinary differential equations in order to solve it.
If all conditions are given at x = 0, it's an easy problem: Define z(x) = integral_{x'=0}^{x'=x} d*sqrt(1+y'(x')^2) dx' The ...

13 days ago | 1

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How can I correctly implement this Meijer G-function in MATLAB for the given equation with specific parameters ?
a,b,gamma,y1 and y2 are given as numerical values ? Then use a = ...; b = ...; ggamma = ...; y1 = ...; y2 = ...; a1 = -y1...

16 days ago | 0

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How to solve a five equations systems to get the five unknown
Directly use the five experimental values (T_exp,theta) as numerical data and "lsqcurvefit" or "fmincon" to solve for the five u...

16 days ago | 0

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piece wise function for thermal properties in PDE solver
When creating the geometry for your problem, I'd already take into account these two spatial regions where the different thermal...

17 days ago | 0

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Netwon algorithm with backtracking is failing
rng('default') n = 2; m = 20; c = sym('c',[n 1]); A = sym('A',[m n]); b = sym('b',[m 1]); x = sym('x',[n 1]); f = c.'*x - ...

17 days ago | 0

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Answered
Averaging specified number of points around the minimum value
data(ix-5:ix-1) are the 5 points left to the minimum, data(ix+1:ix+5) are the five points right to the minimum. So the code sho...

18 days ago | 1

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Can anyone help me to run this coding?
OdeBVP returns NaN for ff(3) at the start (see above). You will have to find out the reason (initial values for y, x, parameters...

18 days ago | 0

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Trying to create code which solves a BVP using a second-order finite difference scheme and Newton-Raphson method
% Code to calculate the solution to a % nonlinear BVP with Dirichlet and Robin BCs % Some physical parameter. mu = 10; % De...

19 days ago | 0

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finding the value at a specific time from second-order ODE
The easiest (maybe slightly inaccurate) way is to use interpolation: f_conv = interp1(time,x,2.5) f_ode45 = interp1(time,y(:,1...

19 days ago | 2

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Inverse fft doesn't match analytical formulation
syms w F = 1/w^2; ifourier(F); disp(char(ans))

19 days ago | 1

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How do I convert symbolic values to numerical for uitable ?
syms x f = x^2-2; xsol = solve(f==0) class(xsol) xvpa = vpa(xsol) class(xvpa) xnum = double(xsol) class(xnum)

20 days ago | 0

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I am getting the error message "unable to find symbolic solution" using dsolve.
What exactly am I doing wrong? Nothing. "dsolve" is simply not able to find an analytical solution because the problem is too ...

21 days ago | 0

Answered
I keep getting the "not enough inputs error" and I don't know how to fix it
m1 = 135; m2 = 30.3455; w1a = .220; w1w = .780; w1m = .000; w2m = .202; w2w = .798; w2a = .000; syms x [6 1]; F(1) = w1...

21 days ago | 0

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Nonlinear constraints depend on the output of optimization objective
Define the constraints using a lower bound of 0 for x(1) (you can prescribe this in the array lb) and one linear constraint (you...

22 days ago | 1

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