Computational Science Questions, Problems & Solutions : TransWikia.com ~ Page 23

When and when not to use automatic differentiation

I am just learning (more) about automatic differentiation (AD) and at this stage it kind of seems like black magic to me. The second paragraph of its Wikipedia...

Asked on 04/22/2021 by tmph

1 answer

Stochastic differential equation system (SDE) : overflow encountered in double-scalars

I'm trying to integrate the following SDE system from Dekker et al. To do that I'm using the ...

Asked on 04/22/2021 by Mathieu Rousseau

0 answer

Error too large in leapfrog method for solving the wave equation of a vibrating string

I have been trying to figure out what I did wrong for the last two days. I do not know if I actually did something wrong or if the error...

Asked on 04/20/2021

1 answer

MPI_Test not progressing MPI_Isend/MPI_Irecv requests

I am running a CFD simulation with a 200,000-vertex mesh. I've decomposed the mesh into 2 load-balanced sub-domains to test my parallel implementation. In the specific function that I am...

Asked on 04/18/2021

1 answer

How does gmres method iteration behave for this non-diagonalizable matrix?

Recently, I have been studied my lessons about gmres iteration, probably the most popular iteration method for general large sparse linear system of equations Ax=b. And the convergence is obtained...

Asked on 04/17/2021 by sunshine

4 answer

A priori error estimates - finite element method - mixed boundary conditions

Consider the problem$$ left{begin{array} {rcl}-Delta u & = 0 & text{ in } Omegau & = 0 & text{ on } Gamma_Dfrac{partial...

Asked on 04/16/2021 by Beni Bogosel

0 answer

'Eigen' matrices with static dimension

I noticed that 'Eigen' matrices with dynamic dimension are less efficient than the matrices with static dimension. My algorithm uses a lot of matrices which don't need to be resized,...

Asked on 04/15/2021

1 answer

Dirichlet Boundary Condition finite difference method using sparse-matrix $Ax = b$ system

I am trying to solve the boundary value problem for heat equation: $$u_{xx} + u_{yy} = f(x,y)$$ where the solution $u(x,y) in [0,1] times...

Asked on 04/14/2021

1 answer

Checking singularity of a matrix

Suppose that we don't know $n times n$ matrix $A$ explicitly but we are only able to compute products $Ax$ where $x$ is a column vector...

Asked on 04/14/2021 by Tommi Höynälänmaa

5 answer

What's the state of the art in parallel ODE methods?

I'm currently looking into parallel methods for ODE integration. There is a lot of new and old literature out there describing a wide range of approaches, but I haven't found...

Asked on 04/13/2021 by Florian Brucker

3 answer

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