# Tagged Questions

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### Add arrows to the solution trajectories using ode solver?

I have a system of two odes and i want to plot the phase portrait with arrows and clearly representing the stable and unstable steady states. The problem is that i am getting the solution trajectories ...
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### Solve system of first order ODEs when values are a matrix

I have a set of first order ODEs such that $$\frac{d \Psi}{ds} = H(s)\Psi$$ H(s) is an 8x8 matrix. I would like to find $\Psi(b)$ where $b$ is 10, for instance. The initial value for $\Psi(a)$ is ...
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### Book for ODEs and numerical solution

I would like to ask you information for a book. I want to (self) study ordinary differential equation and their numerical solution (with MATLAB). I am not a math student (life science) so I want a ...
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### How to solve an ODE with boundary conditions using Matlab solver?

My question is very simple: I want to plot a graphic for the deflection of a beam, with consists of a solution of an ODE using a Matlab solver, such as: %Call Solver -> Linear [x y] = ...
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### How can I solve an ODE when $F(x_0)=F'(x_0)=0$ is given at an unknown point $x=x_0$ using bvp5c?

I'm attempting to solve the following ODE using MATLAB bvp5c. I've used bvp5c for other typical multipoint boundary value problems but I have no idea how to deal with ODEs with conditions given at an ...
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### How can I write an SDE in Matlab?

My professor would like me to solve a system similar to the following: $$dx_i=[f_i(x_1,x_2,...x_n)]dt + g_ix_idW_i$$ Where $g_i$ are positive constants that measure the amplitude of the random ...
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### Using event function in matlab ode45 for multi-dimensional state vector

I have a set of odes written in matrix form as $X' = AX$; I also have a desired value of the states X_des. $X$ is a five dimensional vector. I want to stop the integration after all the states reach ...
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### Matlab ode45 numerical solution

I'm trying to solve a 2nd order differential equation, using the Runga Kutta's ode45 function in Matlab. It's for a bachelor project, where I'm trying to simulate the behavior of a spherical robot, ...
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### Logistic Equation with MatLab

I want to write a MatLab file that can solve the following logistic equation: $$\frac{dN(t)}{dt} = [a-bN(t)]N(t) \;\;\;\; a>0, b>0$$ But I'm not sure how to go about it. Are there any examples ...
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### Matlab: plotting y against f(y) [closed]

I am learning about Matlab and autonomous differential equations and have been trying to plot the graph of y against $f(y)$ for the logistic equation but it doesn't seem to come out right. this is ...
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### SIR models - help!

I am doing a project on the spread of infectious diseases and I have chosen to model this spread by using the SIR model - (susceptibles, infectious, recovered). I have to insert data into this model ...
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### Using Runge Kutta 2 on a System of Equations

So I created a MatLab code to solve an ODE equation, however I'm having a hard time vectorizing everything! Here is the code as I have it: ...
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### Laplace equation in 1D with MATLAB - Neumann boundary condition

My previous problem is here and I 've done. Laplace equation in 1D with MATLAB I have the next problem: solve Laplace equation in $1$D with boundary condition $u'(0)=u'(1)=0$ Help me some hints. ...
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### MATLAB Finding Difference of two equations

So I'm trying to figure out how to do a fairly simply mathematical task in MATLAB but I don't know what it is called so I don't know what to search. Basically what I want to do is if you have two ...
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### Laplace equation in 1D with MATLAB - Dirichlet boundary condition

Here is a Matlab code to solve Laplace 's equation in 1D with Dirichlet's boundary condition u(0)=u(1)=0 using finite difference method ...
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### Ordinary differential equations with signed first derivative

Consider the following coupled set of ordinary diferential equations: \begin{align} (K_{pa}+K_r)y_1(t)-K_ry_2(t)+C_0\operatorname{sign}(\dot{y}_1(t))\lvert\dot{y}_1(t)\rvert^\alpha &= ...
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### Solving a nonlinear system of differential equations in MATLAB or Mathematica

Is it possible to solve the system $$\dot{W}=A\left(k-\frac{M}{W}\right)$$ $$\dot{M}=B\left(k-\frac{M}{W}\right)$$ with initial conditions $$W(0)=w_0$$ $$M(0)=m_0$$ in MATLAB or Mathematica? If so, ...
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### How to plot a phase portrait for this system of differential equations?

I beg your help.. I'd like the phase portrait for this system. I don't know how to use Mathematica/Matlab ... :( If anyone can make this portrait and post a print screen here, I would thank you ...
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### MatCont continuation data for use on other plotting softwares

I have been using MatCont for generating continuation figures for my model ODEs. Dissatisfied with the quality of figures on MATLAB, I want to use gnuplot for plotting of this continuation data. In ...