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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);...

mehr als 2 Jahre vor | 1

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How to find same values in a randi function
Hand = randi(13,[1,5]) arrayfun(@(i)nnz(Hand==i),1:13)

mehr als 2 Jahre vor | 0

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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...

mehr als 2 Jahre vor | 0

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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...

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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 ...

mehr als 2 Jahre vor | 0

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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...

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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...

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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...

mehr als 2 Jahre vor | 1

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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 ...

mehr als 2 Jahre vor | 1

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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: ...

mehr als 2 Jahre vor | 0

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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(...

mehr als 2 Jahre vor | 1

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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...

mehr als 2 Jahre vor | 0

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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 ...

mehr als 2 Jahre vor | 0

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Error using vertcat Dimensions of arrays being concatenated are not consistent..
Most probably: second_derivative = diff([0, diff(Ida_normalized(i:window_end))]); instead of second_derivative = diff([0; dif...

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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 ...

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

mehr als 2 Jahre vor | 1

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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);...

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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...

mehr als 2 Jahre vor | 0

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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...

mehr als 2 Jahre vor | 0

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How can I multiply a row vector with each of two column vectors?
t = [1 2]; s = [(1:3)',(4:6)']; kron(t,s)

mehr als 2 Jahre vor | 3

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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...

mehr als 2 Jahre vor | 0

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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...

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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...

mehr als 2 Jahre vor | 0

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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 ...

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ODE45 solver returning constant value as the input variable.
As you can see when you run the below code, p is in the order of 1e12 which makes dL/dt effectivly 0. Check your units. %Def...

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The code does not converge
I seems your function does not vary much with rho. The evaluation cannot find a value for rho for which the function has a zero....

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How to plot the error of two numerical methods on the same graph?
%% Given data f=@(x) 8-4.5*(x-sin(x)); df=@(x) -4.5*(1-cos(x)); x0=1; tol=0.0001; n=50; [x_newton,i_newton,Error_newton]=n...

mehr als 2 Jahre vor | 1

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Modifying the objective function in order to meet the optimization variable boundaries
if (A <= 1e-04) & (A >= 4e-04) How can A be <= 1e-4 and >= 4e-4 at the same time ? And if-statements have to be done elementwi...

mehr als 2 Jahre vor | 0

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Solve a matrix equation
D = eig(A) will give you the values for D for which det(A-DI)=0

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Solving goal programming problem with MATLAB
x0 must be a vector of size 1x5, not 1x4. Further, your function must return a vector of length 4, not 3. Further, the first o...

mehr als 2 Jahre vor | 0