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odeToVectorField takes forever to run

Are you sure you want to differentiate with respect to functions of t (like theta1, theta1_dot, theta2_dot) ? drn1 = diff(r1,th...

circa 14 ore fa | 0

Solve second-order ODE with Robin boundary condition

syms x y(x) A B C a b dy = diff(y,x); eqn = diff(x^2*dy,x)-2*y == 0; cond1 = A*dy(a)+B*y(a)/a == 0; cond2 = A*dy(b)+B*y(b)/b...

circa 14 ore fa | 0

I want to solve the Lyapunov equation with matlab

Use MATLAB's "lyap" or "dlyap".

circa 20 ore fa | 0

Is matlab able to solve a system of coupled PDE and ODE?

Setting c = 0 in "pdefun" deletes the time derivative of the respective equation and makes the equation an elliptic one. But y...

circa 20 ore fa | 0

graph is the not plotted as desired because of tolerance level

dydx(5) = (-t4./(1-1i.*H1)).*y(4); instead of dydx(5) = (-t4./(1-1i.*H1)).*y(3); in your function definition. I didn't look...

1 giorno fa | 0

| accettato

Having trouble with lsqcurvefit for a heat transfer experiment.

The calls to lsqcurvefit must be h_freebrass = lsqcurvefit(T_free_brass2,10,x,T_free_brass) h_freecopper = lsqcurvefit(T_free_...

1 giorno fa | 0

Error using pdepe Unexpected output of PDEFUN. For this problem PDEFUN must return three column vectors of length 2

The size of "f" is 4x1 instead of 2x1 (see above). Further, if your x-mesg starts at r=0 and you choose m=2, it must hold that ...

1 giorno fa | 0

| accettato

How can I plot a graph by varying two parameters a and b in system of ODE at the same time?

A = [1;2;3]; B = [2;3;4]; C = 10000; d = 2; e = 5; g = 1; tspan = [0 5]; for i = 1:numel(A) a = A(i); b = B(i);...

2 giorni fa | 1

| accettato

How to find same values in a randi function

Hand = randi(13,[1,5]) arrayfun(@(i)nnz(Hand==i),1:13)

2 giorni fa | 0

how can I calculate my expression with double integration?

Maybe you mean this, but I'm not sure: D = 100; e_f = 1.88e-18; m = 9.11e-31; k_b = 1.38e-23; h_bar = 1.05e-34; ksi = 1e-9...

3 giorni fa | 0

I need to solve a system composed by four coupled equations: three ODE and one algebric non-linear equation.

You can try a differential-algebraic solver like ode15s that accepts a mixture of differential and algebraic equations by defini...

3 giorni fa | 0

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fsolve with bound constraints - transformation method

Transformation and initial values are two independent problems that both have to be solved. You cannot compensate "bad" initial ...

4 giorni fa | 0

implicit numerical method: 1-D unsteady state heat transfer using finite difference method

pde() function pde() % Constants Ly = 0.0015; % Total thickness of the system (meters) T = 40; % Total s...

4 giorni fa | 1

| accettato

Interpolating data to get values at specific depth

Make X and Y also 224x164x37 (just by repeating the planar profile 37 times) and use interp3 to interpolate to the depth of your...

5 giorni fa | 2

| accettato

How can I find the vector that simultaneously maximizes my two functions?

Usually, you can't find a vector that maximizes both of your functions simultaneously. You can compute the pareto-front for your...

5 giorni fa | 1

Solving nonlinear system of PDE by using finite difference method for spatial and RK4 for time derivative?

You need two boundary conditions for Tap, one boundary condition for Tsg and one boundary condition for Tag. Your equation for ...

5 giorni fa | 0

PDE solve with bvp4c

Take a look here on how boundary value problems with two regions (in your case -1 to 0 and 0 to 1) have to be set up for bvp4c: ...

6 giorni fa | 0

Solve a system of nonlinear differential equations

Define the unknown functions as y(1) = F, y(2) = dF/dx, y(3) = G, y(4) = dG/dx, y(5) = H. Then the equations are dy(1)/dx = y(...

6 giorni fa | 1

I need some help to solve non-linear equation with three unknowns and three knowns with having 170 different values for one known.

M = [eta+1,Rz,-Ry;-Rz,eta+1,Rx;Ry,-Rx,eta+1]; M = repmat(M,170,1); b = []; for i = 1:170 b = [b;Xw(i)-Tx;Yw(i)-Ty;Zw(i)-Tz...

7 giorni fa | 0

How can I skip the rest of an if statement?

Also in for-loops, "break" only exits the inner structure, but the outer loop runs until the end (see below). Thus you cannot ...

7 giorni fa | 0

Surface plot doesn't correspond to optimization solution

The problem is now, when I select a point randomly in the surface plot, and then calibrate the model for these values, I do not ...

8 giorni fa | 0

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Solving an equation with symbolic matrix

https://uk.mathworks.com/matlabcentral/answers/1918100-error-using-solve-with-symmatrix-equation

8 giorni fa | 1

A group of 12 people all roll a pair of dice 12 times, how often does each person roll a total number that is greater than or equal to 7?

In my opinion, it should be roll1=randi(6,12); roll2=randi(6,12); total=roll1+roll2; GT7 = total>=7; totalGT7 = sum(GT7,1);...

8 giorni fa | 1

| accettato

error in for loop

u(j-3) is only defined for j>=4, u(j+3) is only defined for j<=length(R)-3. Similar restrictions hold for the other indices. Thu...

8 giorni fa | 0

I'm suppose to plot the response of the system but i'm getting wrong values

alpha is a constant , and this is the value of it , I doubt that the rate of change at t=0 for x(5) should be 2.55e17 as you g...

9 giorni fa | 0

How can I multiply a row vector with each of two column vectors?

t = [1 2]; s = [(1:3)',(4:6)']; kron(t,s)

9 giorni fa | 3

final value of x in PDE

i want to solve this equation for r at given time and concentration I assume that the time for which you want to get r is in th...

10 giorni fa | 0

How to prevent substrate concentration going below minimum limit in fed batch fermentation model.

You can use the "Events" option of the ode integrators to interrupt and restart integration with different settings if a certain...

11 giorni fa | 0

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How can I ensure that the initial solution (x0) for fsolve does not result in Inf or NaN values?

You know your "external_fun" best. Try to deduce in advance which inputs will lead to failure. Maybe you can use "lsqnonlin" ins...

11 giorni fa | 0

Huge minimum value from expected results

I cannot run this code because it takes too long or maybe the matrix exponential cannot be computed analytically. Does it give ...

11 giorni fa | 0

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