# Questions tagged [nonlinear]

Used to mark questions about nonlinear differential equations, NonlinearModelFit, and related to nonlinear dynamics.

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### Insufficient memory in Nonlinear Model Fit with ParametricNDSolve

I try to fit parameters to ODE solver with chemical kinetic eqations: ...
• 117
167 views

### Solving 3D Nonlinear Integral Partial Differential Equation

I am trying to solve Equation number (1.2) numerically in MATHEMATICA. This equation is solved in the papers https://arxiv.org/pdf/2205.05193.pdf, https://arxiv.org/pdf/2202.13264.pdf, and https://...
55 views

### How to properly fit experimental data to a nonlinear model?

So I'm trying to fit experimental data to a nonlinear model using the NonLinearModelFit command, but it isn't quite working. The plotted data set looks like this: The data is to be fitted with ...
1 vote
106 views

### Plotting the solution of nonlinear 2-dimentional system of ODEs

I am new to Mathematica, and I have a 2-D system of ODEs: dx/dt=y dy/dt= -x+x^3-2my Mathematica code: ...
85 views

### Nonlinear complex ODE system modeling modified harmonic oscillator coupled to quantum harmonic oscillator

I'm using NDSolve for a system of non-linear ODEs. Here is my code ...
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523 views

• 879
120 views

### NONLINEAR EQUATIONS cannot get the solution

I have simplified the equations and decrease the variables to 5, and changed the parameters' value as I think the equations in enter link description here is because of the improper parameters' value. ...
• 19
1 vote
106 views

### FindRoot::jsing: Encountered a singular Jacobian at the point when solving NONLINEAR EQUATIONS

I have tried many methods to solve the following nonlinear equations. ...
• 19
1 vote
71 views

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### Nonlinear differential equations - follow- up question

I have never solved numerically differential equations and in an optimal control problem I got this one that I cannot solve: $$1-f’(x)^2+f’(x)(x +1)+f’’(x)-f’’(x)f’(x)-f’’(x)f’(x)^2=f(x)$$ The initial ...
157 views

### How does FindRoot decide if a solution has converged?

I am solving a 1D non-linear differential equation using the finite element method with NDSolve. From the documentation I understand that the equation is discretized and then solved with FindRoot, I ...
• 127
307 views

### Nonlinear differential equation numerical solution+plot

I have never solved numerically differential equations, but in an optimal control problem I got this one that I cannot solve: $$1-f’(x)^2+f’(x)(x +1)+f’’(x)-f’’(x)f’(x)-f’’(x)f’(x)^2=f(x)$$ I do not ...
233 views

### I am trying to solve nonlinear Schrödinger equation with dipolar interaction

I am trying to solve numerically Equation number (29) with the help of Eq.(32) and (34) from this paper https://arxiv.org/pdf/1506.03283.pdf. for ...
62 views

### Solving a system of four non-linear differential equation

Could someone help me with my problem? I've been scratching my head over this for a day now. I can't write the right code to solve this non-linear differential equation system: ...
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