Questions tagged [c++]

A powerful object oriented programming language.

Filter by
Sorted by
Tagged with
0
votes
1answer
54 views

Extracting data from VTK simulations using C++

I have been given a few numerical simulations regarding fluid mixing and have been asked to extract a few parameters from them using C++. Altogether there are about 1000 VTK files per simulation, and ...
1
vote
4answers
1k views

Which C++ Multi-objective Optimization libraries allows the addition of custom problems and custom algorithms?

I'm working on a custom discrete and constrained multi-objective optimization problem and I'd like to know which libraries or platforms that implement algorithms like ...
2
votes
1answer
76 views

FFTW on subarray with MPI

With the guru interfaces of FFTW, I can apply transforms only to parts of a multidimensional array by modifying the fftw_iodim ...
0
votes
0answers
51 views

4th Order Adams-Moulton Method C++

I am trying to solve an ODE using 4th Order Runge Kutta and the 4th Order Adams-Moulton Method. I iterate over a couple of thousand timesteps and it seems to hold fine when the values are constant(...
1
vote
4answers
11k views

What's the simplest way to graph a 2d array generated in C++ using Windows 7?

This was so much easier in Python (so much so that I'm considering going back to matplotlib for data analysis). But really, trying to figure out ROOT and Boost graph library and mathgl makes me want ...
1
vote
1answer
60 views

Reading VTK file into C++ for analysis

I apologize in advance if this post is at all ignorant or elementary, I am a pure mathematician who is newly getting into the world of scientific computing. For my research, my advisor would like me ...
0
votes
1answer
38 views

How to calculate error in successive over relaxation for PDE?

I am trying to solve the Poisson equation numerically using the FDM method in C++. But I have a little confusion with the iterative process. I understand that the number of iterations should go until ...
1
vote
1answer
90 views

Calculating the Strange Attractor of the Duffing Oscillator in C++

I am simultaneously trying to learn computational physics methods, chaos, and C++. I think this is the right site for the question, and I apologise if not. I started working through Thijssen's ...
13
votes
4answers
3k views

Looking for Runge-Kutta 8th order in C/C++

I would like to use Runge-Kutta 8th order method (89) in a celestial mechanics / astrodynamics application, written in C++, using a Windows machine. Therefore I wonder if anyone knows a good library / ...
1
vote
2answers
81 views

Writing code on the CPU while developing, running it on the GPU when live - which approach?

In my simulations I am using dense matrix-vector multiplications and 2D-fft transformations quite often, for matrix sizes of 8kx8k and up. Hence, I assume that using a GPU is beneficial for speeding ...
3
votes
1answer
326 views

The Formula of Explicit Runge-Kutta Fourteen order

I need an explicit Runge-Kutta 14th order formula. If you know about some reference that discusses at least 10th order (or higher, since I'm looking for the 14th) of Runge-Kutta and there is ...
5
votes
2answers
266 views

Recommended language/environment for large scale semi-continuous biological models

We have a fairly large (maybe 1000 equations) differential-algebraic equation model written in ACSLX, an obsolete modelling environment similar to Modelica. The model represents the evolution of a ...
1
vote
2answers
115 views

How to begin writing scientific codes in C++ in Trilinos or PETSC style?

My background: I have taken some courses on numerical analysis during my PhD and read a few books on the topic as well. I mostly work on low Reynolds number fluid mechanics and use boundary element ...
9
votes
1answer
1k views

How to document math formulations in scientific computing codes?

I am writing the code relate to math. There is some complicated math formulation in the project. Directly writing the calculation code leads to hard understanding; thus I want to comment on the ...
2
votes
1answer
78 views

Dense decomposition of very non-square matrices

I have inherited code that solves Eigen::Matrix problems using the code shown on this page: ...
2
votes
0answers
19 views

CUDA and implicit array expansion

I am retrying this question since I didn’t do so properly last time: I have implement a simply c++ CUDA example that takes A [m x 1] and B [1 x N] and adds them element wise with what I am used to ...
0
votes
0answers
61 views

Calculating the exponential of a complex matrix

I am trying to calculate the exponent of a 3 x 3 matrix using the formula $\sum_{i=0}^\infty\frac {A^n}{n!}$ I believe that my error may lay in the scalar division with a factorial or the member ...
1
vote
1answer
117 views

C++ - Starting paraller instances of an executable from a C++ code

Can I start parallel run of LAMMPS from inside a C++ code. Is it possible to compile my code and then do mpirun with my compiled code. I also have one system command inside the code, which starts ...
3
votes
3answers
3k views

In C++, how do you calculate the analytical value of $\int_a^b \left|\sin x \right|\,dx$?

How would I find the definite integral (between any 2 limits, say a and b) of the absolute value of sin(x)? I can calculate for the interval 0 to Pi, and from 0 to 2*Pi, but what if the user enters a ...
3
votes
1answer
112 views

How to justify using available code (in different language) for comparing algorithms

I have proposed an algorithm for a scheduling problem in a submitting paper. In the revision, the reviewer asked us to compare with another algorithm from the literature. Our algorithm is in MATLAB, ...
1
vote
1answer
70 views

Finite Difference libray C++

What is the best FD library (or collection of libraries) for C++ codes? I am looking for some data structure implementation that offers the possibility to do parallel computations on adaptively ...
3
votes
1answer
119 views

Suggestions for scientific computing projects to undertake to sharpen core skills

Currently I am completing all exercises in books like "Introduction to Python for Science and Engineering, David Pine" and "Guid to Scientific Computing in C++, Pitt-Francis, Whitley". I am looking ...
26
votes
9answers
3k views

Modern C++ in scientific computing?

I am looking for books or articles, or blog-posts, or any published material in general, that address specifically the uses of C++ modern features (move semantics, the STL, iterators, lazy evaluation, ...
2
votes
0answers
29 views

Whi are chi-squared distributions in (C++) boost::random and C++ STL faster than in boost::math?

I am trying to generate random chi-squared numbers in C++, according to some degree of freedom (which can be a float). Several libraries can be used for that purpose, among which the C++11 Standard ...
2
votes
3answers
179 views

Generating Random Orthogonal Matrices in C++

I'm looking for an open-source library for the generation of random n-dimensional orthogonal matrices in C++. In python, it looks like such a function is available in the NumPy package. But I was not ...
29
votes
5answers
2k views

What features do users need from an MPI C++ interface?

The 3.0 version of the MPI standard formally deleted the C++ interface (it was previously deprecated). While implementations may still support it, features that are new in MPI-3 do not have a C++ ...
0
votes
3answers
103 views

How to store a TB size array in C++ on a cluster

I want to do a huge simulation that requires ~ 1 TB of data to describe a bunch of interacting particles (each has different interactions). Is it possible to store this data in an array in C++, so ...
15
votes
2answers
308 views

What are new c++20 features that are relevant to scientific computation?

In my research department we plan a small seminar on the new c++20 language standard. There are exhaustive lists online presenting the new features of the language standard, some of which will be of ...
2
votes
1answer
178 views

C++ book recommendation- Scientific computing and C++

I'm a master's student in Math interested in Numerical Analysis. I know there are lots of questions like that on this site, but I think this is the best place to ask. So, I'm looking for an ...
1
vote
1answer
74 views

Is C++ and Object-Oriented Numeric Computing for Scientists and Engineers by Daoqi Yang still relevant?

I'm looking to learn C++ primarily from a scientific computation perspective. The approach of the textbook seems ideal to me as it covers C++ from first principles with an emphasis on numerical ...
19
votes
5answers
3k views

Parallel Scientific Computation Software Development Language?

I want to develop a parallel scientific computation software from scratch. I want some thoughts on which language to start. The program involves reading/writing data to txt files and doing heavy ...
1
vote
1answer
61 views

Using adolc for the sign function in c++

Here is an implementation of the sign function in C++ using Adolc librairy for automatic differentiation. ...
0
votes
0answers
145 views

Ising model simulation offset critical temperature and interal ernergy

I'm writing a code for the Ising model using WHAM (the weighted histogram analysis method),But it seems to produce critical temperature and internal energy wrong. (newest rewritten code is below) <...
2
votes
1answer
137 views

How to perform an eigendecomposition of a general complex matrix with arbitrary precision in C/C++

I need to obtain the Eigenvectors of a general complex matrix, but with quadruple precision. Is anyone aware of a means to do this? I currently use Tux Eigen, and I see that in their unsupported ...
2
votes
1answer
83 views

Gmsh meshes flat faces incorrectly for cylindrical faces

I have some C++ code that generates meshes from step files and then analyses these meshes for visibility of the faces from different viewing directions. I currently use CGAL but I would like to switch ...
3
votes
3answers
142 views

GPGPU computing, software selection

I am using an existing GCC C++ x86 Qt application that filters, displays and stores results computed by some C code. Since the computation by now got too complex for CPUs I intend to port the small C ...
9
votes
1answer
408 views

Is using std::valarray considered good practice?

C++ has had the std::valarray class since the C++98 standard. It is meant to facilitate numerical computations, providing the sort of operations one would expect of ...
4
votes
2answers
426 views

overflow upper incomplete gamma function

I want to calculate the following equation: $$\frac{\theta \Gamma \left(\kappa+1,\frac{o}{\theta }\right)-o \Gamma \left(\kappa,\frac{o}{\theta }\right)}{\Gamma (\kappa)}+o+s$$ with $s>0, o>0, ...
16
votes
2answers
2k views

Boost::mpi or C MPI for high performance scientific applications?

The thing I dislike most about MPI is dealing with datatypes (i.e. data maps/masks) because they don't fit that nicely with object oriented C++. boost::mpi only ...
21
votes
10answers
14k views

Fast, lightweight C++ tensor library for dimension-agnostic code

I am looking for a C++ tensor library that supports dimension-agnostic code. Specifically, I need to perform operations along each dimension (up to 3), e.g. calculating a weighted sum. The dimensions ...
1
vote
2answers
1k views

2D Ising Model, heat capacity decreases with lattice size

The problem I'm trying to make a metropolis simulation of the 2D Ising model. Basically, it's the following, for each monte-carlo step: Visit each lattice site, Compute energy required to flip ...
1
vote
0answers
60 views

How to deal with a huge system of ODEs in Boost ODEINT?

I am using the C++ library ODEint, which is part of Boost, to solve an extremely large system of coupled ODEs - in particular 1975 equations with large rational functions in the coefficients. In the ...
3
votes
1answer
52 views

PETSc - Manipulate BAIJ matrix locally

My program loads a parallel PETSc matrix $A$ on several MPI processes, each holding a block submatrix $A_i$. I would like to retrieve the local submatrix $A_i$, the one corresponding to the current ...
2
votes
0answers
37 views

Algorithm to join hexahedra and obtain outline volume

I would like to join several hexahedra and obtain an outline volume. First, I started with 2D implementation. In 2D, there are non-intersecting quadrangles which always touch each other as shown in ...
0
votes
0answers
78 views

How to read data from simply formatted text file (c++)?

Mesh information like points, faces and cells is to be stored into separate files: e.g. for points file: # points data: x y z N_Points 100 x1 y1 z1 x2 y2 z2 ... cell file: # cells data: ...
8
votes
9answers
878 views

Do I need to learn C?

I am a PhD student in Scientific Computing and over the past few months, I spent a good amount of time learning Python and C++ the right way. I feel that I have learnt C++ well and I can use Python to ...
1
vote
0answers
109 views

C++ Library: What is the Most Efficient Library that Factorizes a Polynomial?

I need to know what library is the fastest one that can factorize a polynomial of large degree whose coefficients are big integers. I have tried NTL library to factorize a monic polynomial but it is ...
3
votes
0answers
136 views

Derivative of Whittaker-Shannon interpolant

Last time we looked at how to improve the accuracy of Whittaker-Shannon interpolation, where user njuffa demonstrated that judicious use of sin_pi could greatly ...
17
votes
3answers
3k views

C++ Best practices for dealing with many constants, variables in scientific codes

I am developing a code to simulate fluid flow with biological substances present in the flow. This involves the standard Navier-Stokes equations coupled to some additional biological models. There are ...
2
votes
1answer
102 views

Automatic differentiation via ADOL-C and the Heaviside Function

I am writting a c++ program in which I define a function $$\displaystyle F(t) = \sum_{i}r_i\,H(t-t_i)$$ where $H$ is the heaviside function, $t_i$ are optimal parameters which are mutable. The ...

1
2 3 4 5 6