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Numerical algorithms for problems in analysis and algebra, scientific computation

2 votes

Quadrature rules exact for given functions

Yes, such rules can be derived in the same way that is done for polynomials. Given arbitrary basis functions $\phi_i(x)$, the quadrature rule $$\int f(x) dx \approx \sum_i c_i f(x_i)$$ will be exact …
David Ketcheson's user avatar
2 votes

Global Error Analysis of Euler's Method

Any analysis of global error must include information about how local errors are amplified in subsequent steps. So your statement I know that the local error at each step of Euler's method is …
David Ketcheson's user avatar
2 votes

Frozen coefficient method (von Neumann stability analysis)

I believe the intended reference regarding parabolic PDEs is: Fritz, John. On integration of parabolic equations by difference methods: I. Linear and quasi-linear equations for the infinite inter …
David Ketcheson's user avatar
2 votes
Accepted

Real solutions for systems of monomial equations

As @Oleg Eroshkin has already pointed out in the comments, this is closely related to solving a linear algebraic system. You could take absolute values and then logs to obtain a linear system of the …
David Ketcheson's user avatar
4 votes

Discrete gradient on point clouds

Very many numerical methods for partial differential equations compute derivatives from values on something that is not a regular grid (they use unstructured grids). Usually these are finite element …
David Ketcheson's user avatar
1 vote
Accepted

IVP accuracy - scheme accuracy Vs. derivative accuracy?

In general, when solving a PDE numerically, both the spatial and the temporal discretization will (of course) contribute to the local truncation error and hence to the global error. In many equations …
David Ketcheson's user avatar
2 votes
Accepted

root solving without analytic derivative

Obviously, within the realm of piecewise-smooth functions one can find examples where any derivative-based approach fails. I believe you're looking for the term "derivative free optimization". He …
David Ketcheson's user avatar
4 votes
Accepted

Benchmark Systems for ODE Solvers - Reference Request

There is a whole subfield of applied mathematics devoted to developing ODE solvers and understanding their properties. Consequently, there are thousands of relevant papers, and not much more can be s …
David Ketcheson's user avatar
0 votes

Does an implicit Runge Kutta scheme applied on a nonlinear ODE give a nonlinear set of equat...

This is not a research-level question; the answers can be found in any undergraduate text on the subject. it looks to me as if f(y,t) is nonlinear the system of equations determining ki will also …
David Ketcheson's user avatar
5 votes

Basic software libraries for numerical analysis using modern programming languages?

There are several good answers already, but none of them so far deal with high performance computing, which nowadays means computing on tens or hundreds of thousands of cores. I am aware of only thre …
2 votes
Accepted

Is is preferable to use a difference formula of higher order of accuracy for spatial derivat...

You could use the method of lines to solve this PDE. If you use an explicit finite difference method, you will need to take a rather small time step (${\mathcal O(\Delta x^3))}$ due to the $u_{xxx}$ …
David Ketcheson's user avatar
4 votes

numerically track spectrum curves of a parameter dependent linear operator

I faced this problem a few years ago. In that case, I obtained a satisfactory approach along the lines of one of your suggestions. Specifically, I found that the eigenvectors changed relatively slow …
David Ketcheson's user avatar
1 vote

convergence of finite difference method for boundary value ODE

A very straightforward explanation is given in R.J. LeVeque's text. In Chapter 2 there are simple explanations of how to show convergence for the linear problem in both the maximum norm and the Eucli …
David Ketcheson's user avatar
5 votes
Accepted

Euler method (and others) for unbounded intervals

Regarding 1 and 2: Perhaps the main reason for considering only bounded intervals is that numerical analysts are interested in provably (pointwise) convergent schemes. At least for traditional method …
David Ketcheson's user avatar
1 vote
Accepted

What is the minimum number of stages $s$ required for a Runge-Kutta type numerical method of...

For implicit methods, you can achieve order $2s$ with $s$ stages. Note that this result is the same if one considers the simpler problem of numerical integration (quadrature). Update as of 2024: a 16 …
David Ketcheson's user avatar

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