Tagged Questions

Questions on the symbolic (DSolve, DifferentialRoot) and numerical (NDSolve) solutions of differential equations in Mathematica.

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The result didn't come out and it was written that “step size is effectively zero; singularity or stiff system suspected” [duplicate]

I am tying to solve two differential equations with two delays numerically. The input is given by the picture below. I have tried the methods that have been posted in the web but it didn't work. ...
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How to prevent extrapolation in Manipulate? [duplicate]

How can I limit the time slider to the NDSolve solution range in a Manipulate box, so no extrapolation is used ? More specifically, here's a stripped down version of my Manipulate code which shows ...
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Integrating an interpolating function

I have been using the following NDEigensystem command to generate the eigenfunctions of the laplacian with a square domain: ...
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General solution for a linear ODE set with complicated coefficient

This is the original problem that motivated me to ask this question. I encountered it when trying to reproduce the deduction in this paper. (I'll paste the relevant part below to make this question ...
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NeumannValue and FiniteElement Methods : BC not respected

I have noticed on several of my personal cases some issue with the BC using NeumannValue. Let me illustrate the problem. I take the 1D example of ...
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Can i get step by step calculation of results obtained in mathematica? [duplicate]

In mathematica we generally obtain direct result instead of step by step analytical calculation. Can we somehow obtain these steps?.
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Trying to find a temperature profile with a nonlinear 2nd order ODE. NDSolve very sensitive to seemingly arbitrary constant

I am trying to solve this differential equation for a heat transfer problem: kt\frac{\partial^2 T}{\partial x^2} = \epsilon \sigma T^4, \ \ \ T(0) = T_0, \ \ \ \frac{\partial T}{\...
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How to implement NDsolve for thermo structural code? finite - element - method

I used the following equations to solve a structural problem: ...
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NDSolve Surface Plot to Compare Initial Values

I am trying to solve a system of differential equations which model reaction kinetics using NDSolve. I would like to generate a surface-plot of the function value as a function of time and the initial ...
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Boundary conditions (periodic/anti-periodic) for diffusion equation and NDSolve

I am trying to solve a simple diffusion equation in Mathematica. The problem is inspired by spin diffusion, which is why I consider an initial condition that has both positive and negative density rho[...
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How to specify in NDSolve that the sought function is holomorphic?

If I include the Cauchy-Riemann equations condition in complex form for the sought holomorphic function gf in NDSolve like this: ...
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Plotting the solutions of $y' = -\frac{\cos y}{\sin x}$

I struggle with the problem of plotting the solution of this ODE: $\qquad y' = -\frac{\cos y}{\sin x}$ I've already tried to use ContourPlot in a loop and in a ...
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Using the Levenberg - Marquardt algorithm to minimize a user-defined function

I wrote a function in Matlab that optimizes another user defined function using lsqnonlin with 'levenberg-marquardt' option. Now, I'd like to use the first to ...