Questions tagged [testing]
Questions on the testing and verification of computational methods.
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Nonlinear Hyperbolic PDEs: Known solutions
I would like to collect some test-problems for nonlinear hyperbolic PDEs (Euler Equations, Shallow Water Equations, Ideal MHD, Acoustic Perturbation, ...) for which analytical solutions are known.
A ...
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Where can I find matrices and it's preconditioner for testing?
I want to find some kinds of matrices for testing my code such as GMRES , MINRES and so on. But I can't find some testing matrices and corresponding preconditioner to verify my program.
I know some ...
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What are some good strategies to test a floating point arithmetic implementation for double numbers?
For IEEE, the single representation is 1-bit sign, 8-bit exponent and 23-bit mantissa. This means that at each exponent value, you can test all 2^23-1 (roughly 9mil cases) possible combination of ...
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Verification of coupled system of equations for light propagation
I am trying to simulate the propagation of light in material using the non-linear schrödinger equation (NLSE):
$$\partial_zE=\frac{i}{2k_0}\nabla^2_\perp E+\frac{ik_0n_2}{n_0}\vert E\vert^2E-0.5\beta^{...
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Causes for different results for different number of nodes in MPI
I am trying to develop what might be called legacy Fortran code from my group. Upon testing, I found that the program (which takes about a day to run on 20 processes) works when run on a single node (...
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Which 2D PDE with an exact solution can I use to test/verify my FEM-PDE code?
I have created a program to solve 2D, time-dependent PDEs with the finite element method and get reasonable looking results for the 2D acoustic wave equation. Now I would like to go further and solve ...
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Are there testing frameworks for numerical software development
I found that a lot of my computational science programming has testing requirements that are not covered by standard test frameworks:
Computation time testing
To make sure that algorithms don't get ...
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Poorly conditioned, easily evaluated sum for unit testing
I am looking for examples of poorly conditioned sums which can rapidly be evaluated, for the purposes of unit testing.
I'm currently using the series representation for $\ln(2)$:
$$
\sum_{n=1}^{\...
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Testing Wiener process splitting in adaptive-step SDE integrators
I am investigating various methods for adaptive-step integration of stochastic differential equations and trying to implement them. All of the papers that I've seen (e.g. H. Lamba, J. Comp. App. Math. ...
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2D Test cases for overset meshes
I developed a parallel 2D overset mesh (chimera) assembler and I would like to test a large scale problem. I don't want to make up a test case myself but rather want something standard. Would you ...
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Naming scientific output files
What's the best practice for naming output files from scripts that you're experimenting with? I'm trying different parameters in my data generation script and I'd like to keep track of which files ...
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testing derivative approximations
I'm writing a library that involves some approximations of variational calculus problems. Whenever I implement routines to evaluate the derivative or Hessian of an action functional $A$, I write a ...
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Test matrices for large sparse overdetermined system of linear equations
I'm working on some c++ code to solve (conjugate gradient, least squares conjugate gradient, LSQR,..) large sparse overdetermined systems of linear equations. There is a twist to my matrices and the ...
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Strange convergence behavior of WENO5 for Hamilton--Jacobi equations
I have the following question. I have a code function that computes right-biased and left-biased approximations of the derivative of a function using WENO5 for Hamilton--Jacobi equations as described ...
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How to choose a simple manufactured solution for Euler equation?
In order to verify a two-phase subsonic compressible isothermal Euler code, I am trying to implement a manufactured solution following what is discussed here and references therein. Also, as an ...
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1D uniform flow test case for compressible flow
Are there any one dimensional hyperbolic test cases for a 1D uniform flow?
(I need the test case for the purpose of showing the satisfaction of geometric conservation law on a moving mesh).
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Coriolis test problem
I have a eulerian hydrodynamic code, which I have recently implemented the Coriolis force in the integrator. Is there a standard test problem for the Coriolis force?
Since this isn't a Lagrangian ...
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How close observed order of accuracy should be to theoretical order of accuracy?
I try to write tests to the implementations of numerical methods.
The best way to do this is to study the observed order of accuracy and check that it matches with the theoretical order of accuracy.
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How can I compare errors in PDE solvers with non-uniform grids?
Is there a standard approach to testing codes with refined regions? Specifically, I am interested in testing whether the refinement is working correctly.
For the sake of simplicity, let's consider a (...
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What are the good testing problems for hyperbolic equation?
I read the whole list of this question: Where can one obtain good data sets/test problems for testing algorithms/routines? But the answers are in different areas and I want to ask a specific area.
I ...
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Test Case with Known Solution for 3D Navier Stokes Equations
Is there a test case for 3D incompressible Navier Stokes Equations like the Taylor vortex in two dimensions?
I know, I can easily construct 3D manufactured solutions but I would like to have ...
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How to write integration tests for numeric simulation software?
Just to be more precise, I'll put a worthy example of my typical use case.
Let's say I'm developing a FEM software that produces several temporal solutions and inserts them in an HDF5 file, along with ...
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Testing 1D root-finding procedures for robustness
How can I test whether a given 1D root-finding procedure is robust? I know that there are data sets and resources online for different kinds of optimization, but I have yet to find anything with ...
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Test set for linear solvers
Lets assume I have a iterative linear system solver, e. g. this one.
Whats the typical approach on verifying and testing this kind of solvers? Is there a standard test set of linear systems one ...
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Local versus remote development
I know there are similar questions asked on other StackExchange sites, but I think development in Computational Science may work differently because of the computing environments that are common. I ...
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Guidelines for choosing manufactured solutions for numerical PDE schemes
When testing a numerical method for a PDE, I know that it's often useful to compare it to a known analytical solution. If none is available, one can always 'manufacture' a solution, substitute it ...
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Looking for analytic solutions to time dependent fluid flow problems
I'm looking for analytic solutions to time dependent fluid flow problems (can be compressible or incompressible, Euler or Navier-Stokes equations). The main thing though is that I'd like there to be '...
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Any recommendations for unit-testing frameworks compatible with code/libraries that use MPI?
Usually, I write serial code, and when I do, I write unit tests with some xUnit-style testing framework (MATLAB xUnit, PyUnit/nose, or Google's C++ testing framework).
Based on a cursory Google ...
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Strategies for unit testing and test-driven development
I'm a huge advocate of test-driven development in scientific computing. It's utility in practice is just staggering, and really alleviates the classic troubles that code developers know. However, ...
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Test case suggestion for incompressible flow with ALE method on deforming grids
I'm working on a finite-volume discretization method with implicit time-integration for the incompressible Navier-Stokes equations in Arbitrary Lagrangian-Eularian (ALE) form. So far I've tested the ...
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Testing suites for numerical applications in C++?
Recently, I've been pushing my group to include more testing when writing their code. There were several major bugs that took a lot longer to catch than probably speaking was necessary, because we ...
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Is there any 1-D test case for incompressible flow codes?
There is quasi 1-D C-D nozzle test case for compressible flow codes, like that "is there any 1-D test case for incompressible flow codes?"
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How to obtain the minimum set of variables required in a model to produce accurate estimation?
I have a system which I assume is linear. I have a matrix $A$ of which each row is a coefficient of a unknown variables in vector $x$. I have vector $B$ which contains the result of each $Ax$.
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Testing and visualizing large index arrays
I will be implementing nodal discontinuous Galerkin method soon, and having done this before I know the basic indexing arrays I will need to compute, given a mesh and polynomial data.
The problem I ...
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Regression testing of chaotic numerical models
When we have a numerical model that represents a real physical system, and that exhibits chaos (e.g. fluid dynamics models, climate models), how can we know that the model is performing as it should? ...
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Test set non linear solver
what is your preferred test set to test quality of non linear solver?
this could be set of data, model and results obtained with some benchmark solver, or simply a panel of test functions that could ...
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Databases of results for numerical codes
In the numerical methods literature, many research papers consist of a description of a new algorithmic variation, followed by a few test problems comparing the new method with one or two existing ...
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Is it worthwhile to write unit tests for scientific research codes?
I am strongly convinced of the value of using tests that verify a complete program (e.g. convergence tests), including an automated set of regression tests. After reading some programming books, I've ...
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What programming strategies can I take for easily modifying algorithm parameters?
Developing scientific algorithms is a highly iterative process often involving changing lots of parameters that I will want to vary either as part of my experimental design or as part of tweaking ...
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Where can one obtain good data sets/test problems for testing algorithms/routines?
In evaluating the quality of a piece of software you are about to use (whether it's something you wrote or a canned package) in computational work, it is often a good idea to see how well it works on ...