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, ...
724 views

NDSolve giving a wrong solution

Consider the ODE $$\frac{y'y}{1+\frac{1}{2} \sqrt{1+ y'^2}}=-x.$$ Using NDSolve[{-x==y'[x] y[x]/(1+Sqrt[1+(y'[x])^2]/2), y[0] ==3}, y, {x,-7,7}] and plotting leads ...
574 views

Why does NonlinearStateSpaceModel linearise?

The documentation for NonlinearStateSpaceModel says: In NonlinearStateSpaceModel[eqns, ...] the Taylor linearization is with ...
1k views

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

Consider the following test case: ...
701 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: ...
509 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 ...
680 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 ...
230 views

Geometrically nonlinear beam deflection

Edit only for those interested in large deflections of beams I discovered a mistake in the equations of the original question (below): in the normal force (compression/traction) ...
457 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 SchrÃ¶dinger-Newton equation if that's more familiar to you. \begin{align} i \...
350 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 ThiÃ©venaz et.al and was interested in knowing how they obtained the graphs presented. From what I ...
239 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 \$\...
345 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: ...
130 views

Can we construct our own NDSolveStateData?

NDSolve can be broken into three stages: NDSolveProcessEquations processes the equations and sets up an NDSolve`StateData ...