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How could I have these two erros when I did everything right (otherwise)?
c_p defined in your script does not mean that it is also visible in your functions. Either define the functions as nested funct...

mehr als 2 Jahre vor | 0

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Problem with solving two differential equations depending on each other
Since W0 = 0, you get Re = 0 and thus lambda = something undefined (you divide by Re !). What does the c stand for in dm^3/c fo...

mehr als 2 Jahre vor | 0

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How to plot function with different first x values?
I = @(R)0.5*(R>=0 & R<10)+5/R*(R>=10 & R<=100); U = @(R)0.5*R*(R>=0 & R<10)+5*(R>=10 & R<=100); P = @(R)I(R)*U(R); R = 0:0.1:...

mehr als 2 Jahre vor | 0

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Why eigen vector looks different than the calculated one
Eigenvectors are only unique up to a multiplicative constant, and MATLAB's eigenvectors are normalized to be of norm 1: [1;-3]/...

mehr als 2 Jahre vor | 0

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Paramter optimization using fmincon
It seems that the model is not able to reproduce your measurement data. The curves look qualitatively different. clc; clear; ...

mehr als 2 Jahre vor | 0

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i make a code of shooting method for 3rd order differential equation but i dont get the accurate result
y20 = 2; sol = fsolve(@fun_shooting,y20); [X,Y] = fun_ode(sol); plot(X,Y(:,1)) function res = fun_shooting(y2) [X,Y] = ...

mehr als 2 Jahre vor | 1

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Non linear system by Newton-Raphson
x1 = 1; y1 = 1; P = [x1 ; y1]; F= @(x,y) [atan(y)-y.*x.^2 ; x.^2+y.^2-2*x]; JF = @(x,y) [-2.*x.*y (1/(1+y.^2))-(x.^(-2)) ;...

mehr als 2 Jahre vor | 2

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need help getting this to run
Maybe initial_strain_index = find(colum1 == min(colum1),'first'); peak_stress_index = find(colum3 == max(colum3),'first'); in...

mehr als 2 Jahre vor | 0

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How to visualise the 'output' of a Neumann boundary condition?
I think the example "Heat Transfer Problem on a Square" under https://uk.mathworks.com/help/pde/ug/pde.stationaryresults.eval...

mehr als 2 Jahre vor | 1

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Can PDE solver pdepe handle discontinous initial conditions?
Depends on the equation(s) you want to solve. If there is much diffusion in your equation(s), usually yes. Else usually no.

mehr als 2 Jahre vor | 1

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one of the terms "Rho_net" on the RHS of an set is varying with time over the tspan. How do I implement the set of the ODEs such that the term updates at every time step?
If you insert the line size(dYdt(tspans(1),initial_conditions)) before the call to ode45, you will see that your function dYdt...

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Newton Raphson gives answers divided by 0
Your linear systems in the course of the Newton iterations cannot be solved since the Jacobian is rank-deficient (it has only ra...

mehr als 2 Jahre vor | 1

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I am wanting to delete these entries of vector x when x = 0. How do I do this. Matlab gives me an error right now saying index cannot exceed 38 but I don't know what's wrong.
Use x(x==0) = []; instead of for i = 1:56 if x(i) == 0 x(i) = [] end end The length of the x-vector wil...

mehr als 2 Jahre vor | 0

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I am trying to create a while loop where a marker can't leave a box of x = -10 and y = 10, y = -10. Once the marker reaches x = 11 I want the loop to stop.
Put the k = k+1 at the end of the while-loop, not at the beginning. And if x(k) == -10, you only set x(k+1), but not y(k+1). Th...

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solving for y in equation
a = 85.147; h = 55; v = 50; u = 25; f = @(x,y)x-sqrt(a^2+h^2)-(h-y).*cot(asin((h-y)/v))+(h-u)*cot(pi/4-asin((h-y)/v))+v*sin(...

mehr als 2 Jahre vor | 0

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Iteration loop for a function to reach a certain value.
g=9.81; NU=2.52; k=.0293;%from book L=.025;%plate to cover spacing m sigma=5.6697e-8; epsilonp=0.95;%plate emittance epsil...

mehr als 2 Jahre vor | 0

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Why do I have a never ending loop ?
The initial condition at t = 0 seems to be T = 4 for all x in your code. But you must set boundary conditions for T at x = 0 an...

mehr als 2 Jahre vor | 0

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Multi objective optimization for genetic algorithm showing out of bound solutions.
If you plot x(:,2) against x(:,1), you will see that both respect the bounds you prescribed: figure(2) [x1,idx] = sort(x(:,1))...

mehr als 2 Jahre vor | 2

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Please help to solve the error in evaluating a system of odes using ode45
Rho_net is an array of length 365, but it must be a single scalar value in ode_2. If you want to evaluate the array at time t g...

mehr als 2 Jahre vor | 1

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Solving the differential equation by the Runge-Kutta method (ode45)
[t, y] = ode45(@odefun2,[0 3],[1,0]); plot(t,y(:,1)) function dfdt = odefun2(x,y) w = 2e16; r0 = 30e-6; c = 3e8; ...

mehr als 2 Jahre vor | 0

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Breaking down a numerical integration into two parts
I1 = dx/2 * f(x0) + dx * sum_{i=1}^{n-1} f(xi) + dx/2 * f(xn) I2 = dx/2 * f(xn) + dx * sum_{i=n+1}^{n+m-1} f(xi) + dx/2 * f...

mehr als 2 Jahre vor | 1

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simple x.y plot
Use y = (4*(x.^2)*log(6))+(5*(x.^2)) ./ sqrt (cos(x).^2) +1 instead of y = (4*(x^2)*log(6))+(5*(x^2)) / sqrt (cos(x).^2) +1...

mehr als 2 Jahre vor | 0

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I'm receiving this error: "Incorrect number or types of inputs or outputs for function int." when trying to run the following code. I think because of the symbolic variables
syms a1 a2 a3 a4 theta dzdx = a1*pi*cos(.5*pi*(1-cos(theta))) + 2*a2*pi*cos(pi*(1-cos(theta))) + 3*a3*pi*cos(1.5*pi*(1-cos(the...

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Assumptions are not being considered in symbolic math.
What is rank(A) ? If it's 8, your system of equations has a unique solution, and you can't assume anything about it.

mehr als 2 Jahre vor | 3

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Need help to fit the data without error.
I assumed you start integration at x = 5.3571429. You will need to specify dr/dx and dtheta/dx in the y0-vector below. rData =...

mehr als 2 Jahre vor | 0

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Do ODE solvers use location of root of event function in its solution even if integration isn't specified to stop?
You will have to tell the solver to return control to the calling program once the corner point is reached. From there, you can ...

mehr als 2 Jahre vor | 0

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How to debug this? Not getting into it. Need help
Use fit = lsqcurvefit(@(params, x) funr(params, x), initialGuess, rData(:,1).', rData(:,2).'); fit2 = lsqcurvefit(@(params, x)...

mehr als 2 Jahre vor | 0

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role of flux f in bcfun of pdepe for systems of PDEs
This multiplication is nowhere performed within "pdepe". But if you look at the pdepe code below, the cases where q = 0 and q di...

mehr als 2 Jahre vor | 0

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Logit panel with Simulated Maximum Likelihood. Convergence question with fminunc
Your objective function depends on random values. This is not allowed for deterministic optimization as done by "fminunc". Conve...

mehr als 2 Jahre vor | 2

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It keeps giving me an error on line 4, saying I'm missing input arguments but I have everything defined?
Q = 9.4e-6; q = 2.4e-5; R=0.1; epsilon= 0.885e-12; F=@(z)(Q*q*z) .*((1-z)./(sqrt(z.^2+R.^2)))/(2*epsilon); z1 = 0.5; z2 =...

mehr als 2 Jahre vor | 0

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