Linked Questions

41
votes
4answers
2k views

Is there a convenient way to copy/paste text-interspersed SE code snippets into Mathematica?

Is there a way to copy and paste code snippets from SE to Mathematica if these snippets are interspersed with text? Like e.g. in Morphing Graphics, color and location in both the question and answer, ...
9
votes
2answers
565 views

Why does NonlinearStateSpaceModel linearise?

The documentation for NonlinearStateSpaceModel says: In NonlinearStateSpaceModel[eqns, ...] the Taylor linearization is with ...
12
votes
1answer
643 views

Why does NDSolve fail to solve the PDEs and spit out mconly warning?

I try to solve two coupled PDEs with NDSolve using the following code: Set two operators: ...
7
votes
2answers
1k views

Why does NDSolve need to solve for the derivatives if the equations are already explicitly solved?

Consider the following test case: ...
10
votes
2answers
496 views

Bug in NDSolve/WhenEvent?

Bug introduced in 10.3 or earlier and persisting in 11.0 10.0 is not affected I'm fairly sure the following is a bug, and I would normally just report it to WRI. However, this is related to my ...
3
votes
3answers
601 views

NDSolve::icfail for a VERY LARGE system of ODEs

I have a very large system of ODEs (up to several thousands ODEs and up to several hundreds of thousands of various coefficients, which power these ODEs). The ODEs and coefficients are generated based ...
5
votes
1answer
429 views

Variation of heat equation with guessed initial condition

Hi I am trying to solve a variation of the heat equation with interaction terms and external source -- actually it's the Schrödinger-Newton equation if that's more familiar to you. \begin{align} i \...
8
votes
1answer
310 views

Moving B.C.s in heat diffusion model

I came across the paper Solidification dynamics of an impacted drop regarding a heat equations by Thiévenaz et.al and was interested in knowing how they obtained the graphs presented. From what I ...
8
votes
1answer
211 views

Nonlinear elasticity PDE in Mathematica 12

Mathematica 12, Windows 10. I am trying to solve a PDE in one spatial dimension $R$ and time $t$. I need a solution for displacement $r(R,t)$, radial Cauchy stress $T_{RR}(R,t)$, and radial growth $\...
6
votes
1answer
328 views

How to speed up NDSolve when there are ~400k equations?

I'm trying to use NDSolve to solve a set of ~400k equations. The problem I met is: when I ran the evaluation, Mathematica (version 11.0) raised an error: ...
3
votes
1answer
258 views

Shell falling into a black hole in Kruskal coordinate

I am modeling the motion of a shell falling into a black hole in Kruskal coordinate with NDSolve. I am sure that the physics behind it is correct, but can't get the ...
8
votes
1answer
112 views

Can we construct our own NDSolve`StateData?

NDSolve can be broken into three stages: NDSolve`ProcessEquations processes the equations and sets up an NDSolve`StateData ...
5
votes
1answer
109 views

Speed up NDSolve for DAE

I'm handling with a large DAE system with some events (around 400 equations and 20 events) and lots of them are nonlinear. Let's take the equations from this post as an example. ...
4
votes
2answers
154 views

Solving coupled ODEs

I lately faced some problems trying to solve systems of coupled nonlinear ODEs with NDSolve. Cause I couldn't find a solution on my own, here I am with a MWE. Consider a system of $n$ coupled linear ...
3
votes
1answer
91 views

Ideal transformer model (2 ODEs) warning “NDSolve will try solving the system as differential-algebraic equations”

I have a simple electrical circuit of an ideal transformer: I model it in Mathematica 11.3 with the idea to solve for secondary current and potential difference. Here is my code: ...

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