Linked Questions

0 votes
0 answers

Accuracy goal and precision goal [duplicate]

What they do in our calculation I read about these from internet so, the major doubt is if my output is coming say like 2.215478*10^-18 and I put precision goal or accuracy goal 17. Is this result ...
user51734's user avatar
50 votes
4 answers

Funny behaviour when plotting a polynomial of high degree and large coefficients

I am trying to plot a polynomial of degree $29$ on the domain $[0,1]$, with fairly large coefficients: ...
AUK1939's user avatar
  • 1,493
31 votes
3 answers

1D Euler equations (fluid dynamics) with NDSolve

Is it possible to accurately solve the 1D Euler equations in Mathematica using NDSolve? For example, let us consider the Sod shock tube problem. Introduction to ...
partition_of_unity's user avatar
15 votes
3 answers

NSolve gives additional solutions that don't satisfy the equations!

I am trying to solve the following polynomial equations in Mathematica: ...
dbm's user avatar
  • 1,229
12 votes
2 answers

Finite element mesh not resolving features

I am trying to make a finite element mesh in 2D. The features are not found by ToElementMesh. This is a shelf bracket with nails. I build the region using ...
Hugh's user avatar
  • 16.1k
6 votes
5 answers

Problems with NDSolve and stiffness

I am trying to solve an ODE in chemical kinetics: $$\begin{align*} \frac{\mathrm d[x]}{\mathrm dt} &= -k_1 [x][y]\\ \frac{\mathrm d[y]}{\mathrm dt} &= k_1 [x][y] - k_3[y] \end{align*}$$ My ...
l3win's user avatar
  • 705
3 votes
3 answers

NIntegrate fails while Integrate works

I have a function $f(t)$ defined as $f(t)=\int\limits_0^t(t-\xi)^{\alpha-1}\ \cos(\xi)\ d\xi$ where $0<\alpha<1$. I now want to evaluate this integral at various values of time. Therefore, my ...
G. H. Hardly's user avatar
2 votes
4 answers

NIntegrate::ncvb: NIntegrate failed to converge to prescribed accuracy

The integration is: ...
so_sure's user avatar
  • 309
4 votes
2 answers

NSolve for high degree univariate polynomials

I am trying to solve a high degree univariate polynomial using Mathematica's NSolve command. But when I plug the solutions generated by Mathematica back to the equations, the equations are massive ...
John's user avatar
  • 61
7 votes
2 answers

Solving an unstable BVP numerically, accurately and efficiently

About two weeks ago I've posted the following question on MathOverflow: Solving a boundary value problem numerically, with high precision. That is, the ODE is \begin{equation} y''=y^2-t \tag{1} \end{...
user1337's user avatar
  • 1,068
5 votes
2 answers

Is FindRoot wrong about its WorkingPrecision?

EDIT: I filed a bug report and after a small back-and-forth the support person agreed this is a bug. He said: "I have filed a report with the developers to issue warning messages when the arithmetic ...
Max's user avatar
  • 1,040
14 votes
1 answer

Jacobian of ParametricNDSolve and FindRoot for the Three Body Problem

The main problem I took the time to reformulate the question in a more appealing and concise way. I want to find bifurcations of solutions to the three body problem. In order to do that, I define ...
Pragabhava's user avatar
  • 1,599
3 votes
1 answer

Solution gets worse as I increase Precision and Accuracy goals

I am numerically solving the following ODE below. If I set AccuracyGoal and PrecisionGoal both to 10 I get a solution that makes sense: constant and then damped oscillation. However, all things equal, ...
Rudyard's user avatar
  • 451
3 votes
2 answers

Working precision problem in Complex integrand

I'm trying to plot 2d numeric integral of a complex function which is actually real. First problem - small non zero complex part, I was forced to plot RE of it. Second - I'm using only exact numbers ...
satoru's user avatar
  • 133
8 votes
1 answer

Is there any way to speed up this code that's Maximizing a function got from numerical integration?

I have this code below, which is calculating the Binding energy of an electron in a Quantum Well Wire with a hydrogenic impurity in it. Well you don't have to care much about what kind of calculation ...
tyler_house's user avatar

15 30 50 per page