0
votes
0answers
4 views

Batch script for multiple files

I have multiple ascii files like Total-0100.dat and want to batch process using an executable in another directory. In short, 1. I have multiple files with incremnet of 100 or 1000 e.g. ...
0
votes
0answers
5 views

Evolving nonlinear Schrodinger equation with higher-order algorithms?

First I will give the relevant information for my question, and then I'll ask the question. $\large{\textrm{Background}}$ For evolving the nonlinear Schrodinger equation (NLS), one typically uses ...
0
votes
0answers
22 views

Very long running time for Haase and Muller (2014) coded in Python + Gurobi

I have read the paper of Haase and Muller (2014) where they present the linear reformulations of the multinomial logit choice probabilities and compare different approaches. I have tried for an ...
3
votes
0answers
56 views

Increasing the accuracy of numerical discretization

In order to numerically solve the following differential equation: \begin{equation} \text{Fr}\{f\} := v(k)\dfrac{\partial f(z,k)}{\partial z} - F(z) \dfrac{\partial f(z,k)}{\partial k} = ...
0
votes
0answers
49 views

Beowulf Cluster For MD simulations

What would you recommend as an all-in-one cluster management software for a Beowulf cluster? We have about 7(most of them are 8 core machines and 1 is a 48 core machine) very good compute nodes in our ...
1
vote
2answers
79 views

C++ libraries for Fast Fourier Transform in high precision

I am looking for a C++ library for Fast Fourier Transform (FFT) in high precision (e.g., using high precision real data types similar to mpfr_t in MPFR or ...
5
votes
3answers
94 views

Fitting with a linear combination of exponentials

I want to elaborate on a statement I read in Acton's "Numerical methods that work", paragraph "Exponential fitting", page 252. Computationally we are being asked to fit only the parameters $A$ and ...
1
vote
0answers
32 views

Solving Schrodinger's Equation Numerically in a Bunimovich Stadium

I need to solve, as mentioned, Schrodinger's equation in a Bunimovich stadium-shaped infinite potential well with Dirichlet BC Numerically (this isn't possible analytically). In order to do so, I need ...
0
votes
0answers
35 views

what is procedure for crank Nicolson method in nonlinear partial differential equations? [on hold]

can u tell me step by step of what is procedure for crank Nicolson method to apply in nonlinear partial differential equations? and how to plot it.
0
votes
2answers
67 views

MPI+OpenMP Scalability

I have a numerical code which is MPI+OpenMP (hybrid) parallelized and an available computational resource of 32 nodes with 16 cores on each node. The code has been tested for MPI scalability up to 16 ...
0
votes
1answer
40 views

Repeated 1d minimization with similar parameters (scipy)

I have a function f(x,k1,k2) and I am trying to minimize it over x for different values of ...
0
votes
0answers
6 views

In Content Based Image Retrieval, what is Skewness of a colour moment?

In Content Based Image Retrieval, what is Skewness of a colour moment? and would we expect it to be better or worse for providing accurate results?
4
votes
0answers
79 views

Robust smoothers for geometric multigrid

I'm searching for robust smoothers for geometric multigrids. By robust I mean: Effective for high order approximations (say spectral element, spectral Discontinuous Galerkin), Parallel (suitable ...
-3
votes
0answers
20 views

the compiler says cds in resize(cds); is undeclared, Can someone help? [on hold]

//header file /* */ ifndef CDS_STRUCT define CDS_STRUCT include "CD.h" using namespace std; struct CDs { CD** cd_array; int num_cds; int max_cds; }; // CDs* createCDs(string ...
3
votes
0answers
43 views

Methods of solving non-linear advection-diffusion systems beyond Newton-Raphson?

I'm working on a project where I have two adv-diff coupled domains through their respective source terms (one domain adds mass, the other subtracts mass). For brevity, I'm modeling them in steady ...
3
votes
0answers
15 views

Finding errors in frequency from a Fast Fourier Transform from Gaussian fitting

I took a FFT of sound in a box generated by a frequency sweep over a range of frequencies, and have an array of frequencies and their corresponding FFT amplitudes. According to models for the ...
1
vote
0answers
34 views

Fixing a near singular covariance matrix

Given a near singular covariance matrix, the standard method of 'fixing' it seems to be to add a small damping coefficient $c>0$ to the diagonal, which serves to bump all the eigenvalues up by this ...
0
votes
1answer
44 views

On Boyd et al.'s convergence analysis of ADMM: Why do we need the convexity assumption?

Please refer to Boyd et al.'s convergence analysis of ADMM (Chapter 3 and Appendix A). My question is: Why do we need $f$ and $g$ to be convex? I don't see the need of this assumption. If the ...
0
votes
0answers
23 views

How to alter the standard deviation algorithm to extract edges

I have developed a programme that currently computes the standard deviation of an Image Histogram. I am trying to alter this algorithm so that it can extract the edges of an image. I have been told I ...
2
votes
1answer
66 views

Pseudo Code for non linear power function fit needed

I am struggling finding pseudo Code for a non-linear fit of the following function: $y = a\, x^b$ Package NLS in R does perform well, but utilizing external software is not practicable in my program ...
1
vote
0answers
23 views

Minimization of the sum of convex function and non-linear non convex function

I'm trying to minimize the unconstrained scalar sum of a quadratic convex function (to which a convex optimizer is readily applied) and a non-linear and non-convex function which is differentiable. ...
0
votes
0answers
8 views

Starting structure for stacking interaction energy calculation

I have a crystal structure (single crystal, pyranone carboxamide derivative) that shows $\pi$-$\pi$ stacking, and I want to do theoretical calculations. I am using Dispersion-correcting potentials ...
-3
votes
0answers
17 views

please help me to convert 2d monte carlo simulation program for grain growth to 3d [on hold]

function plotgrainsizedistribution(Tmcs2,nodespool) global L0 lembda K1 n1 global coord global num_of_row y1=num_of_row; tmcs=sum(Tmcs2); %summing the entire tmcs value for the each grain ...
0
votes
1answer
104 views

How to solve the problem without using symbolic computation

I have the following simple nonlinear equations with two unknowns only: $$\left\{ \begin{array}{c} \int_1^2{\dfrac{ e^{{a_1} x+{a_2} x^3}}{1+x^2}} \, dx=1 \\[13pt] \int_1^2{ x^2 e^{{a_1} x+{a_2} ...
0
votes
0answers
23 views

Expected runtime complexity of repeated closest Point Pair search

I have to vectors $X_1$ and $X_2$ with 3 dimensional points $p_i$ and $p_j$ contained. As long as $X_1$ is not empty, I want to find the closest pair $p_i$ and $p_j$. The point $p_i$ of this pair I ...
1
vote
0answers
13 views

I'm using linear programming for production planning. Does the order in which I make products affect the cost?

I have a collection of different scrap aluminium alloys. I want to mix them together to make new alloys with customer-defined compositions. Sometimes this will involve little more than melting down ...
0
votes
2answers
24 views

Difference between Data structure objects and cell array objects in matlab

I want to know what are the differences between two data structures in MATLAB: Structure Arrays and Cell Array. In what circumstances we can use each of them?
0
votes
0answers
18 views

Algorithm to group Boolean functions by rotation similarity

I'm looking for a way to take the entire vector space of length n Boolean vectors and partition it into vectors that are the same up to a rotation of the entries. For example if n=3 the partitions ...
0
votes
2answers
19 views

Grouping Boolean vectors by similarity up to a rotation [duplicate]

I'm looking for an algorithm to take the entire vector space of length n Boolean vectors and partition it into vectors that are the same up to a rotation of the entries. For example if n=3 the ...
6
votes
2answers
139 views

Solving $A=B+AB$ without matrix inverse

I have a linear system of equations that can be expressed $$A=B+AB,$$ where $A$ and $B$ are real, symmetric matrices. I would like to solve for $A$ given $B$. At present, I solve for $A$ directly via ...
0
votes
0answers
10 views

Grouping operator in DBMS (Ɣ) is duplicate impervious. Why? [migrated]

I'm reading Database Systems by Ullman where its mentioned that Ɣ is duplicate impervious. I dont understand why a simple group operation should cause elimination of duplicates. Aliter, ...
0
votes
0answers
38 views

Most efficient and practical way to avoid calculating inverse matrix?

So I've heard about the LU decomposition applied to avoiding calculating the inverse of a matrix and how it's so much more efficient than the typical inverse calculating functions in numerical ...
0
votes
1answer
25 views

How to discretize Laplacian near refinement boundary

Given a block structured grid with a refinement factor of two, what are some of the common ways to discretize a Laplacian near a refinement boundary? See also the picture below, in which $u_H$ and ...
1
vote
1answer
14 views

The alternative to using PETSc's SNES solvers in parallel without using the DMDA methods

I am using the PETSc libraries, in particular using the SNES solver package to solve a nonlinear matrix equation. Is there a way of parallelising the solution to this problem problem without using ...
3
votes
0answers
31 views

Numerical computation of the complex elliptic integral $E(k)$ for medium $|k|$

I have implemented Carlson's algorithm for $E(k)$ from Numerical computation of real or complex elliptic integrals (available from ArXiv eprint, see also DLMF). It is essentially his formula (46) ...
0
votes
0answers
12 views

PETSC Makefile dependencies and Netcdf

I have built an interface to PETSC for my main code, contained in coreSolver.cpp so that I can use non-petsc data structures and call PETSC when necessary ...
6
votes
1answer
40 views

Stokes Equation in “two-fold saddle point” form?

Are there papers that deal with the (nondimensionalized) Stokes equation for incompressible fluid flow in a "doubly mixed" form like the following? \begin{align*} 0&=\underline{\epsilon} + ...
0
votes
1answer
53 views

Divide and conquer for optimizing weakly unimodal continuous function?

Is there a divide and conquer algorithm for optimizing weakly unimodal continuous functions? Adding more details: My function has a flat line on the left and right and then there is a global ...
0
votes
0answers
22 views

Will Golden Section Search work for optimizing weakly unimodal functions?

Will Golden Section Search work for optimizing weakly unimodal functions? If not is there any variation of it that will allow for optimizing weakly unimodal functions instead of strictly unimodal ...
1
vote
1answer
37 views

Function similar to erf that is fast at scale and allows for changing the slope at 0?

I'm interested in a function that would allow me to weight my system similar to using the error function; however computing the error function at scale would be a bottleneck. Is there something like ...
6
votes
3answers
352 views

ODEs vs DAE vs ADE?

I am totally confused between ODEs which I am familiar with, and differential algebraic equations (DAE) and Algebraic Differential Equations (ADE). Are they the same but just different names or what ...
1
vote
1answer
40 views

Complex Numerical Integration using GSL

I want to program an integration routine in C++ using the GSL library but for complex functions. How should I split my integrand to apply the gsl_integration_qag function on it. Just integrate the ...
4
votes
2answers
99 views

Matrix representation of the radial Laplace operator isn't symmetric as supposed

I'm working with the cylindrical coordinates. I'm using the central difference to convert the radial part of Laplace operator into a matrix. $\nabla^2 u = \frac{\partial ^2u}{\partial ...
0
votes
0answers
30 views

machine learning to obtain feature vectors of periodic point distribution in 3D [on hold]

Is there some standard procedure (building feature vectors) that could be used to build machine learning models based on discrete and infinite point distributions on a hyperplane (practically 2D 3D)? ...
-3
votes
0answers
25 views

MCNPX simulation [closed]

I want to ask about neutron source in input file. The problem is I have subcritical core, fuel is mixed between thorium and uranium 50 % and I need to put 2 neutron sources in different places ...
1
vote
1answer
49 views

computational complexity for computing perimeter of a polygon

What is computational complexity for computing perimeter of a polygon of $n$ vertices? The polygon is not necessarily regular and can be convex or non-convex.
0
votes
1answer
48 views

Most efficient way to compute eigenvectors / values of this matrix?

I have a symmetric $ 3 \times 3 $ matrix $A$ and I need to compute the eigenvectors and eigenvalues of this. I know that I can use something like Lapack, but I also know that this can be computed ...
3
votes
1answer
79 views

Second order interpolation scheme

On a grid I am having the values of a physical quantity say for example Temperature, at the E,W,N,S and P node all of them being calculated using a second order discretization scheme. I want a second ...
0
votes
0answers
16 views

Feature vectors for infinite discrete distribution of points on 3D space [duplicate]

Is there any standard procedure (building feature vectors) that could be used to build machine learning models based on discrete and infinite point distributions on a hyperplane (practically 2D 3D), ...
0
votes
1answer
23 views

Probability of reconstructing a word using c substrings from a random sample

Consider a voice recording split into it's phonemes as our sample $S=(s_1,...,s_k) \in \Omega = P^k$. The number of phonemes is $|P| = 40$. Then I have a word $w = (w_1,...,w_n) \in P^n$. I want to ...

15 30 50 per page