1
vote
2answers
16 views

use Matlab's PDE toolbox to solve PDE with variable coefficients

I'm new to the PDE toolbox in Matlab. From the PDE specification window of the toolbox, it looks like one can only solve PDE with constant coefficients. How can ...
0
votes
1answer
16 views

Calculating periodicity of a pseudo random number generator (Middle-square method)

Below is a Python code that calculates the periodicity of the middle-square method for a given 4 digit-numbers: ...
1
vote
0answers
24 views

Issues with Open MPI [on hold]

Not sure if this question is more appropriate for StackOverload, but I'm guessing a bunch of people here have experience with MPI2, so thought I would try here first. I have some large dense complex ...
3
votes
0answers
36 views

Numerically compute one-to-one mapping

I have a set of points defined by their coordinates $(x_1,y_1)$ after changing some parameters of the problem I obtain a second set of points defined by their coordinates $(x_2, y_2)$. There exists a ...
0
votes
0answers
7 views

Any software that can symmetrize input sets?

Is there any software that contains symmetrization techniques ex. polarization, Steiner Symmetrization etc. I suppose not. Which software would you suggest for rigid transformations? Thank you
1
vote
0answers
30 views

Comparing Eigenvectors, Mathematica vs. Matlab

I am trying to create the same out puts in Mathmatica and Matlab, however I am running into trouble aligning the eigenvectors with the eigenvalues, I think the Matlab is doing something slighly more ...
1
vote
3answers
54 views

rank-deficient NNLS

I want to find the minimum-norm solution to a rank-deficient least-squares problem, subject to positivity constraints, e.g. $$\min_x\ \|x\|^2 \quad s.t.\quad Ax = b,\ x \geq 0$$ where $A$ is large, ...
0
votes
0answers
18 views

Signal balancing using SVD: notations and implementation in R

Hibbs et. al use SVD to balance the strength of different underlying signals in gene expression data using the following decomposition: $X_{m*n} = U_{m*n} \Sigma_{n*n} V^T_{n*n}$ In this case $U$ ...
0
votes
0answers
15 views

Convex hull and cartesian Product

Under which conditions, the cartesian product of some closed and bounded polytopes is equivalent to their convex hull?
1
vote
1answer
33 views

Fast way to compute all eigenvalues of a dense Hermitian matrix

I am finding the eigenvalues of dense NxN Hermitian matrix which is calculated from a density operator in quantum physics. All the eigenvalues are needed as I need to calculate the sum of the absolute ...
5
votes
0answers
39 views

What is the current state of the art in solving higher dimensional parabolic PDEs (multi-electron Schrödinger equation)

What is the current state of the art for solving higher dimensional (3-10) parabolic PDEs in the complex domain with simple poles (of the form $ \frac{1}{|\vec{r}_1 - \vec{r}_2|}$) and absorbing ...
2
votes
1answer
155 views

0,1 binary polynomial programming

Is there a mathematical optimization branch that explicitly tries to optimize this (type) problem? $$\eqalign{ & \min \cr & \sum\limits_{i = 1}^N {(J*s[i] + {J_1}*s[i]*s[i + 1] + ...
0
votes
1answer
29 views

Appropriate algorithm for (non-linear) ODE with integral equilibrium constraint: collocation?

I have a problem of the following structure: For some scalar $g$, functions $F(z)$ and $h(z)$ defined on $[0,\bar{z}]$ , and a non-linear operator $\phi(F,z)$ (in reality, $F$ and $h$ are vector ...
0
votes
1answer
34 views

Permission denied with diary command

I am trying to use the diary function in Matlab: ...
1
vote
1answer
50 views

Lua and Fortran (or Python) I/O

I am writing a global climate simulation software system. My idea is the following : At the top of everything, I interface to the OS using D, a very powerful language for compile time code ...
0
votes
0answers
15 views

COMSOL: String vibration modeling using Wave Equation PDE

I am learning comsol and already could make the vibration of a string in 1D (geometry used there was an interval) - I saw 2D plot and the string was vibrating, also I could do the same in 2D ...
1
vote
2answers
43 views

Suggestions for open source C++ library for medium scale non-linear solver

I need to find the root of a nonlinear system (which comes out of collocation, so I will change the order to test). I will likely have about 50-300 variables, and the Jacobian is going to be ...
1
vote
1answer
25 views

Solving a problem using multiple threads using CLP

Is it possible to run Clp on multiple threads using Julia and JuMP?
2
votes
1answer
70 views

Levenberg-marquardt: How to calculate the jacobian with fixed parameters

So I'm working on a fitting algorithm using the levenberg-marquardt algorithm and I'm a bit stumped as to how to handle fixed parameters. Looking around at other code, like the minpack version of the ...
-1
votes
0answers
22 views

What are some latest IO devices? Mostly from last five years? [on hold]

I need to prepare a presentation about a latest IO device which was invented in the last five years period. I searched but the internet doesn't have that much detail about the devices. I was thinking ...
2
votes
4answers
102 views

Open source auto-differentiation for MATLAB?

Are there any open-source auto-differentiation libraries for MATLAB? I am aware of commerical packages such as http://tomopt.com/tomlab/products/mad/ and plenty of C++ libraries, but I can't find much ...
9
votes
2answers
131 views

Is it well known that some optimization problems are equivalent to time-stepping?

Given a desired state $y_0$ and a regularization parameter $\beta \in \mathbb R$, consider the problem of finding a state $y$ and a control $u$ to minimize a functional \begin{equation} \frac{1}{2} ...
2
votes
1answer
50 views

Does it make sense to build ATLAS from source on a cloud machine?

ATLAS is an extremely popular linear algebra library. When you install ATLAS from source, it tries to automatically tune a number of parameters to give you the fastest code. Does it make sense to do ...
0
votes
0answers
23 views

I am getting the following error: variable not a function or function pointer for a declared variable in c code [on hold]

What does this mean and solution for it.Coding in dev c. The declared variable is an array.
0
votes
0answers
39 views

ode45 solver MATLAB improve time

I am numerically simulating the Mathieu equation using ODE45 and I have to keep changing the parameters delta and epsilon for each simulation to get the required peiodic solution. Following is the ...
1
vote
1answer
30 views

eigenvalue of small symmetric matrices

If I am to solve a symmetric eigenvalue system $A=QDQ^T$, where $A\in\mathcal{R}^{n\times n}$ and $n$ is small (in the range 4 - 64); I want all the eigenvectors and eigenvalues; There are two major ...
0
votes
0answers
23 views

Generating start point in a systematic manner for fmincon

I'm trying to generate start points for my optimization problem in Matlab. At this point Im not worried about feasibility but only a fast way to generate the points from which I could test the ...
1
vote
0answers
27 views

Generating Hessian of the Lagrangian with dynamic number of nonlinear constraints in Fmincon

I'm using interior point algorithm for solving a nonlinear optimization problem and want to provide Hessian of the Lagrangian as part of fmincon to speed up the process (running couple of thousand ...
0
votes
0answers
3 views

OpenCL C Matrix Multiplication over Multiple Runs

I am attempting to translate a dgemm / MPI matrix multiplier onto the GPU through OpenCL C. My issue is that the code below gives the correct output for a 9x6 matrix being multiplied by a 6x450 ...
0
votes
0answers
36 views

Fast way to compute barycentric lagrange interpolation

Is there any fast way to compute the barycentric Lagrange interpolation using matlab? something more faster than using repmat instead of for loops
0
votes
1answer
24 views

prove optimality only by cutting without branching (gurobi)

I have a MIP which I know the solution almost for certain. I want to use gurobi to prove that the true solution (even if it is not the one i provide) shall not lie more than 0.5% deviated from the ...
0
votes
2answers
93 views

Finite elements beyond the fundamental

After reading three books about finite element method, with two of them covering also finite volume and grid generation, I found myself lost when I have to discuss these topics with library developers ...
0
votes
0answers
28 views

How to create rotating obstacle [closed]

I want to create mesh for channel flow with a rotating cylinder can any one give me the idea? how to do it... I am using fenics FEM solver...
0
votes
1answer
16 views

Should I use bestman2 or dcache CLIs (srmping, srmls, etc..)

I am fairly new to using SRM, and I am wondering if I should be using srm CLI tools (srmping, srmls, srmcp, etc..) provided by dcache, or bestman2 counter parts (srm-ping, srm-ls). I used to think ...
0
votes
1answer
23 views

Algorithm for distributing members over activites (with individual preferences)

So in my school we have a day where everybody participates in different activities. Each projects can have like 10 members. The whole day is divided in 2 or 3 different blocks, in which the pupils ...
3
votes
1answer
76 views

How does matrix-matrix product scale with multiple CPUs?

These days, one can have 64 cores in a single node. I wonder how well the dense matrix-matrix product (SGEMM and DGEMM) scales ...
3
votes
1answer
89 views

Finite Elements Weak Formulation generalization

I am struggling with an equation that represents the Weak form of Galerkin method: $ \phi^{T}F(\textbf{u})\sim \int_{\Omega}^{ } \phi.f_{0}(\mathit{u},\nabla \mathit{u}) + ...
1
vote
0answers
67 views

Python - calculation time derivative and laplacien by finite differences

I would like to determine a temporal derivitive and a Laplacian by the finite differences method to solve the heat equation in a 1-dimensional case. My aim is to get the sources term that is why I ...
4
votes
1answer
57 views

Advice on numerical solution for 2D hyperbolic PDE with zero flux boundary conditions

I would like to numerically solve a hyperbolic PDE of the form $\frac{\partial\theta_t}{\partial t}(x,y)+\frac{\partial\left[\theta_t \gamma_t^x\right]}{\partial x}(x,y)+\frac{\partial\left[\theta_t ...
0
votes
1answer
20 views

Fastest multithreaded radix sort

What is the fastest multithreaded radix sort code out there? I am using radix sort to sort the Morton/Hilbert keys when constructing a tree structure. The number of identical keys is in the range of ...
1
vote
1answer
40 views

Symbolic Computations with Block Matrices in Maple

Due to the derivation of an algorithm I tried to use Maple (9.5) to calculate some block matrix expression. Unfortunately Maple seems to ignore the assumption I set on the variable. Lets consider the ...
0
votes
1answer
43 views

How many years it would take our laptops to be as fast as the fastest super computer in 2000 [closed]

How many years it would take our laptops to be as fast as the fastest super computer in 2000 according to Moore's law?
1
vote
0answers
36 views

Question about ellipsoid method

I have some technical question concerning the ellipsoid method Referring to the paper : http://paswkshop.comm.utoronto.ca/~weiyu/01658226.pdf It is mentioned in p.1317 at the last line in the left ...
7
votes
1answer
90 views

Finite element convergence rates for mixed problems

I've coded up a Stokes Flow problem using finite elements and am in the process of verifying that it works. I'm just not sure what convergence rate I should be expecting as I globally refine the mesh. ...
5
votes
2answers
209 views

Recommendations for symmetric preconditioner

Given symmetric, positive-definite matrix $A$ and its preconditioner $M^{-1}$. What's kind of preconditioner $M^{-1}$ which preserve the symmetry of $M^{-1}A$?
0
votes
0answers
30 views

Lattice Boltzmann Method

I have done Molecular Dynamics Simulation and now want to venture into Lattice Boltzmann Method. What would be the best reference book/lecture notes/videos for a beginner?
4
votes
1answer
59 views

Finite Difference Method Stability

The diffusion equation is: $ \frac{\partial T}{\partial t} = \alpha \left( \frac{\partial^2 T}{\partial x^2} \right) $ An explicit finite difference approach can be used to solve this, forward in ...
3
votes
1answer
49 views

Find a single vector in the null space

I have a single sparse matrix $A$ for which I can easily compute $Ax$ and $A^*x$ and I would like to solve $\min(||Ax||) \text{ s.t. } ||x||=1$. I know the answer is the right singular vector ...
3
votes
1answer
54 views

State-of-the-art for active set optimization algorithms?

Given a problem like this: $$ \text{min } ||Ex-f|| \text{ s.t.}$$ $$ Gx \ge 0$$ $$ Cx = d $$ And assuming that the matrices are medium sized (dimensions in the low thousands) and dense, what's the ...
0
votes
0answers
9 views

dynamically chose PBS queues during job submission

I run a lot of small computing jobs in remote cluster where job submission is managed by PBS. Normally in a PBS (bash) script I specify the queue that I would like to submit the job through the ...

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