Questions tagged [c++]

A powerful object oriented programming language.

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323 views

A programming model for Quantum Mechanics angular momenta in Mathematica

I'm writing prototypes for solving the Liouville Equations with Mathematica and C++. Perhaps the question about this may not be suited for this forum in a strict way, but it suits the people here ...
2
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1answer
106 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 ...
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0answers
35 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 ...
2
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1answer
81 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 ...
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0answers
1k views

Good C++ optimization library for BFGS

To implement maximum likelihood estimators, I am looking for a good C++ optimization library that plays nicely with Eigen's matrix objects. Eigen has some capability of interfacing of its own but if ...
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52 views

Looking for a version of DSDP that is less prone to integer overflows than the original

I am working on a problem that involves semidefinite programming (constrained optimization of fairly large positive definite matrices). The software is written in C++ and calls DSDP 5.8 to solve the ...
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147 views

What could be causing multi-dimensional numerical integration inconsistency?

I'm trying to numerically integrate a multi-dimensional expression. The integrand is complicated; for example this is the integrand for $N=4$: $$\begin{aligned}&x_1^6x_2^5x_3^3x_4^2(x_1-x_1x_2)(...
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0answers
375 views

Using C/C++ for Markov chain Monte Carlo (MCMC) methods

I'm working on optimizing the parameters of a mathematical model to fit experimental data, using an existing formula for the likelihood of observing the data given a set of parameter values. At the ...
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0answers
56 views

Under what circumstances does Elemental's distributed SVD not work? [closed]

I am playing around with Elemental's distributed singular value decomposition and am running into two particular issues. Building the test at tests/lapack_like/SVD.cpp, and running with ...
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95 views

C++: How to find the roots of polynomial modulus N [duplicate]

I need to know what library, given a vector of coefficients and modulus N return the roots of polynomial modulus N. The library should support big integer. I'm coding in C++.
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86 views

Bracket Algebra, Straightening Algorithm

My apologies if the question is simple. I need to write a code for straightening algorithm. Which includes defining bracket algebra. I tried to write it in CoCoA-5, but it wasn't possible because ...
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0answers
120 views

Lapack++ for QR algorithm

I have recently started using Lapack++ which I found convenient for my programming purpose, in general. Now, I need to solve a matrix using QR algorithm. I've searched the user manual and I found a ...
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2answers
182 views

Inverting big symmetric and singular matrices

In this post I found a very similar probem to the one I have, but not a satisfactory answer for my purposes. I have a set of matrices $C_\ell$. They are exactly symmetric by construction. ...
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2answers
2k views

Physics Simulation in C++

OK, I know a bit of C++ (very basic syntax), and I want to do physics simulation in C++, like stuff like (also the things mentioned here): Ripples and waves over a 2-d surface Vibrating string/...
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2answers
335 views

C++ template design pattern for groups (algebra)

Having both programmed my share of c++ and studied some beginners group theory some year ago, I got curious about this... Is there any particularly popular template based (object oriented) design ...
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1answer
3k views

eigenvalues of a general complex matrix in C++

Is there a free C or C++ library including a routine for the eigenvalues of a general complex matrix? I checked a number of linear algebra packages like Eigen, but there does not seem to be support ...
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1answer
784 views

Improve numeric stability of subtraction in C++ [closed]

I'm writing a matrix library in c++. After some debugging I found that a simple double difference is not zero for two "equals" numbers. This is due how double are represented in a computer of course. ...
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2answers
452 views

How does MPI differentiate between two computers?

I am starting to dabble in MPI. I am fairly new to this area and I am currently reading the MPI standard. I would like to write my first MPI program, a simple hello world program, on a cluster that ...
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2answers
804 views

Parallelization of element-wise matrix multiplication

I use Armadillo as an interface to OpenBLAS. In my current program, I have a loop, in which I do multiplications of the form ...
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3answers
888 views

C++ mixed integer nonlinear programming (MINLP) solver

Doing research project in material involving (mixed integer nonlinear programming) MINLP problem, we want to implement MINLP based on C++, because the majority of our project is based on C++. What ...
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1answer
1k views

C+C++ library for inversion of a large scale matrix over cluster

I need to implement a matrix inversion of a very big matrix that currently is exceeding the memory limits of my machine (unfortunately I have little memory running on 32-bit machines). I would like to ...
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1answer
382 views

LAPACK sorting eigenvalues differently each time

I'm using LAPACK zgeev routine to get eigenvalues and eigenvectors of a symmetric matrix in C++. Problem is zgeev is being called in a loop but it sorts eigenvalues (and eigenvectors) differently ...
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2answers
160 views

Sign of integer determinant 4 by 4

I'm in the context of this publication: http://www.gilbertbernstein.com/resources/booleans2009.pdf I applied quantization to my point coordinates: All coordinates are integer lying in [0, 2 power 20]....
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2answers
874 views

GSA Search Algorithm in C++

Is there any version of GSA (Gravitational Search Algorithm)[1] implemented with C++ or even C#? What I found was implemented using MATLAB which is not good for me. [1] Rashedi, Esmat, Hossein ...
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2answers
210 views

Programming language for HPC [closed]

I'm planning on building a program that will carry out HPC. I'm aware that C/C++ is significantly better than Python in terms of the speed of computation. However, I'm not yet proficient in C/C++, so ...
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1answer
827 views

How can I call the Boost C++ odeint Runge-Kutta integrator for a system of ODEs?

I would like to use Boost C++ odeint Runge-Kutta integrator on a system that looks like this : $$\ddot x = - \frac A{||x||^3} * x $$ $ x $ is a vector in 3D space, so basicaly $ x(i, j, k) $ $ \...
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2answers
2k views

Solving the 1D Particle-in-a-Box using C++

I've just finished learning the physics behind the problem and would like to write a program in C++ than can solve the problem. I'm actually stuck at the start. I've quite a bit of research, the ...
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2answers
673 views

LU decomposition of large dense matrices

I wanted to generate LU decomposition of large size dense matrices ($N>10^7$), the LU decomposition I'm currently using is based on Adaptive Cross Approximation and is taking very long time to ...
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1answer
565 views

Is there a single C++ IDE packed with necessary scientific libraries for computing purpose?

I am basically looking for a good open source C++ IDE with scientific and visualization libraries built in. Can any one suggest few projects?
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1answer
64 views

LAPACK DGGEVX: BALANC option

I'm using DGGEVX routine from LAPACKE with BALANC option as shown below, but to my surprise changing BALANC option from 'N' to ...
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1answer
180 views

LAPACK equivalent on c++ , which is the best one? [duplicate]

I am following a course of computational material physics. The professor uses fortran to code and uses lapack to solve eigenvalue problems. So far I just know c++. There is an equivalent library that ...
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1answer
215 views

C++: Efficient library for dense linear algebra operations (determinant & principal minors)

I usually work with Python, but my basic knowledge of c++ allows me to switch when I need to increase the speed of my code. Currently, I have a python script that (among other things) computes the ...
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1answer
694 views

Eigen - Solving Complex Generalized Eigenvalue Problem

I've been using the Eigen C++ linear algebra library to solve various eigenvalue problems with complex matrices. I've recently had to use a generalized eigenvalue solution process, only to be ...
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3answers
997 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 ...
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1answer
238 views

Efficiently rotate vector in 2D (and 3D)

I need to efficiently rotate a 2D (and 3D) vector in a CUDA kernel. I was thinking about generating random unitary rotation matrices. I don't need to know the angle, it just has to be randomly ...
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1answer
5k views

Looking for a C/C++ implementation of the Hungarian method for real-valued cost matrix

I am looking for a C/C++ implementation of the Hungarian method for solving the linear assignment problem with real-valued cost matrix. Some implementation I found, such as this one, only work for ...
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3answers
250 views

Traveling Salesman Problem

First off some context. The Traveling Salesman Problem(TSP) is to find the most efficient route passing through a series of points only once. However, there is no perfect function to solve for this in ...
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1answer
95 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 ...
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1answer
233 views

Windows C++ library for operations on mesh with a mex-interface in Matlab?

Please recommend me a well documented C++ library that I could wrap with a mex-interface in Matlab. The library should have the capability to read meshes (optimal in different formats, at least in ...
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1answer
483 views

How to minimize the artefact of a cartesian to polar transform followed by a polar to cartesian transform?

I'm transforming cartesian images into polar images. (x,y) => (angle, radius) I fill the polar image by iterating on each of its pixels and filling them by doing the reverse polar transform. For a ...
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1answer
146 views

what went wrong with my logistic regression implementation in c++?

I have implemented a simple logistic regression function with IRLS algorithm using the armadillo linear algebra libray ...
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1answer
890 views

Coding complex equations into C++

I have here equations from a paper by E. Bradlow. They're for counting the events in a Weibull-distributed data set. $$\begin{align} \Pr(N(t)=n) &= \sum_{j=n}^\infty{\frac{(-1)^{j+n}(\lambda t^c)^...
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1answer
1k views

How can I reuse the SVD of matrix A to solve LS problems for both A and its transpose via Eigen C++?

If $A\in R^{m\times n}, b\in R^m, c\in R^n$, if I need to solve the least square problems via SVD of $A$ and $A^T$, i.e. I need to solve the least square solutions to following linear systems via ...
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0answers
39 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 ...
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0answers
41 views

Metis: how to use and tutorial recommendation

I am new to METIS and trying to use it in my fortran code. I read the manual online. But still, I am not sure about how to implement it my code. I tried the test cases in the graphs directory. For ...
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0answers
45 views

How to integrate the contents of a vector using an adaptive quadrature routine [duplicate]

I have a function which requires the return type to be a container. The problem is that I need to integrate the contents of the container as efficiently as possible and was hoping to use adaptive ...
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0answers
48 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 ...
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0answers
99 views

$ A * B $ computation when B is a symmetric matrix in armadillo [closed]

Is there any way to multiply a symmetric matrix by a dense one in armadillo(and use the fact that we have a symmetric matrix)? I know about DSYMM Routine in BLAS,...
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0answers
54 views

Dense decomposition of very non-square matrices

I have inherited code that solves Eigen::Matrix problems using the code shown on this page: ...
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2answers
725 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 ...