# Tag Info

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### Post Processing of Solution and Plot of Coupled Partial Differential Equation Over a Semi-Circular Domain

I can't get the same exact plot for the second part. This is what I get This is the code. Feel free to change it as needed. ...
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### Solution and Plot of Coupled Partial Differential Equation Over a Semi-Circular Domain.II

Since you used NDSolveValue to solve the first PDE, then you can use that solution in the second PDE using sol1[r,θ] and not as ...
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### NDSolveValue result contradicts initial condition

Let's have a look at the mesh that is automatically generated: Needs["NDSolveFEM"] mesh = ToElementMesh[rg] Now, we evaluate the ic at the coordinates ...
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### Solve Differential Equation Numerically

First, consider the case d = 0: eq0 = y''[x] - Exp[y[x]] + Exp[-2 y[x]] + 1; with y' == 30 and ...

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### Plot general solutions

Mathematica does not give an explicit solution, because it can't integrate the integrals. In addition, even it it did, you can't plot the solution since $A$ is not known. Even giving $A$ a numerical ...

### A way to generalize my code for this non linear ODE problem

Here is an example how to solve for F. ...
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### Solving differential equation with hyperbolic functions

These is a simple integral problem ...
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### How to plot a differential equation?

If Q,a are given constants your equation gives an implicit result x[R] ...
1 vote
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### FEM solution for onedimensional boundary value problem doesn't evaluate

That's a typo: You used "MaxCellMeasure->0.1" but you should use: "MaxCellMeasure" -> 0.1

### How to numerically solve symmetric top with fixed point motion equations with Mathematica?

This is Manipulate of Symmetric top gyroscope motion. It has many options to explore the dynamics. I wanted to improve it more, but no time now. But it works and has many options to play with. Code <...

### Solving Geodesics from Christoffel Symbols

In an earlier comment I made, I mentioned that the term Exp[g[t] + f[r]] was common to all the spatial terms in your metric, and that you might want to consider factoring the exponential and ...
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### Axisymmetric cylindrical Laplace's equation with a boundary condition at infinity

Oblate spheroidal coordinates are ...

### How to force Wolfram solve the ODE with respect to h[s]?

but what should I print? Mathematica can't solve it analytically. Even if you replace all other terms by parameters ...

### How to reduct the terms of differential equation?

The dots . in the definition of detG seem to be wrong I think Try ...
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### Mathematica thinks that an initial condition is a boundary condition

Here is a way to solve it. Note that there is no need for the NeumannValue, as the 0 NeumannValue is the default. I have changed the initial condition on R and gave ...
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### Set of differential equations with trigonometric functions and a derivative squared

In this post we answer the question how to extend periodic solution t[y] up to $4 \pi$ and how to compute solution in a case of ...
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### Modeling Infection Spread among Different Age Groups with Contact Matrix

I really enjoy your epidemic series :-) It is always better to decouple the weedy details of a specific model from the key question. Key question should be purified to bare minimum. Perhaps helpful, --...

### Set of differential equations with trigonometric functions and a derivative squared

Try numerical solution NDSolve[...,Method->"StiffnessSwitching"]. Solutions seem to be complex, is this intended? ...
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### The Poincaré Sections of Yang-Mills-Higgs System

I'm currently co-developing an interactive tool for extracting Poincaré sections from Hamiltonian systems. I've got a preliminary version up and running, so feel free to use it. It's available on the ...

### The Poincaré Sections of Yang-Mills-Higgs System

If we take icv from your second example and define Hamiltonian as ...
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### Evaluation and plot the result of NIntegrate obtained from NDSolve

Your definitions (keep h undefined) ...
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### Solving coupled differential equations involving the square of the derivative

There are 2 branches in the analytical solution with variable p=pt, ...

### Solving coupled differential equations involving the square of the derivative

I'll let you do the plotting. But these are not coupled ode's. The y[s] ode does not depend on t[s]. So you can solve that on ...

### Solving Geodesics from Christoffel Symbols

On my first post, I found the geodesics equations found from Christoffel symbols: ...

### Solving Geodesics from Christoffel Symbols

Euler-Lagrange equation for geodesics produce the Christoffel symbols as coefficients of the products of velocities in the equation of motion, solved for the second order derivatives of the ...

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### How to numerically solve symmetric top with fixed point motion equations with Mathematica?

The use of the Hamilton function (energy) in terms of the velocities for deriving equations of motion is always a dangerous mistake. Use the Lagrangian equations (trivial with two constant angular ...
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### Second order Poisson ODE

This is some sort of a scaling problem: ...

### NDSolve problem with conservation laws

Replacing one IC seems to work: ...
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### Plot several graphs of a function density distribution using Table

DensityPlot has the Attibute "HoldAll": Attributes[DensityPlot] {HoldAll, Protected, ReadProtected} Therefore, if you want to evaluate "ps[B]" ...
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### Need help solving cylindrical Laplacian

You'd need to use Cartesian coordinated (or use a RegionSymmetry). Something like this should get you started: ...
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### How do I get a coefficient matrix from a second order ODE's system?

Looking what you have done aboove in your ask, I did it (turn a 2nd order ODE system in 4 equations 1st order ODE system). But, as I said, I need to comper this 2 situations (2nd order ODE system, ...