0
votes
0answers
5 views

Free HFSS alternative to create geometry using python

I am using a python script to create wirebond interfaces in Ansys HFSS. Variables define the board, wirebond, and package geometry. To simulate a new wirebond, I just edit the geometry variables and ...
1
vote
0answers
28 views

Image recognition on Raspberry Pi

I'd like to distinguish different types of beers in my fridge using a Raspberry Pi. I saw a very good tutorial on Adafruit that utilized OpenCV for face recognition. Can these same face recognition ...
2
votes
1answer
65 views

High frequency noise at solving diffusion equation

I'm trying to simulate a simple diffusion based on Fick's 2nd law. ...
6
votes
2answers
145 views

Representing Eisenstein numbers without floats

I have a project where I need to use quadratic fields Specifically numbers of the form $a + b \sqrt{-3}$ with $a,b \in \mathbb{Q}$. For example here are the prime numbers in Eisenstein integers: ...
0
votes
0answers
8 views

plot issue in Comsol Multiphysics

I'm dealing with an Axisymmetric 2D model in Comsol Multiphysics. In other words I working in cylindrical coordinate system. Now I need to build a graphic which represents a changing of some variable ...
0
votes
0answers
14 views

Mass-conservative reprojection (on a sphere)

I have a 2D distribution of mass on a sphere given as a matrix of masses in latitude-longitude grid cells. I need these masses projected to another grid on the same sphere with different location of ...
2
votes
1answer
52 views

Large binary programming problem

I have 10000 variables (each of them is binary), vector of positive coefficients and a matrix A (10000*10000), if Aij is 1, then ith and jth variables can take 1 simultaneously, if it's 0, then it's ...
1
vote
0answers
15 views

Scheme to alleviate (numerical?) instability in system of coupled nonlinear ODEs

I'm solving a system of nonlinear ODEs that take the form $Q_{nm} \ddot{y}_m + S_{nkl}\dot{y}_k\dot{y}_l +V_n = 0$ where Einstein summation is assumed, $y_i$ are the dependent (complex) variables, ...
1
vote
0answers
17 views

What's the most efficient way to calculate the Wiger quasiprobability distribution?

I want to calculate the Wigner quasiprobability distribution function of a particular wavefunction. The definition suggests a few straightforward ways of calculating it, but I was wondering if there's ...
1
vote
1answer
38 views

Sparse quadratic programming solver

For a hobby project I need to solve a series of quadratic programming problems each with about 500 variables about 1000 constraints, each of the form $x_i-x_j\le c_{ij}$ the objective function is ...
3
votes
1answer
100 views

Publishing a software package along with a paper: licensing

I want to publish the software package I've written for my graduate work along with a paper describing the package. So far I've been considering liberal licenses such as BSD. However, I am now aware ...
0
votes
0answers
10 views

Any relation between the singular values of each flattening matrices and the core tensor out of Tucker decomposition?

Before I know how to do tucker decomposition, I mistakenly thought the core tensor is only from combining the singular value matrices of the flattening matrices. Yes I know it is not now. For the ...
0
votes
1answer
39 views

Least squares fitting

I have the following equation I came across which was solved using least squares $x = \sum_{n=1}^{N} A_{n} y_{n}$ Where $x$ is a $m \times p$ matrix and $y$ would be of size $m \times p$ as well ...
1
vote
1answer
35 views

Optimization of a sum of an absolute vector

$$ Mimimize\ \sum\limits_{i=1}^{10} L_{i}x_{i} \\ subject \ to \\ Af=p\ \\ x \geq|f| \\ L, p \ and\ A\ are\ known,\ f\ and\ x\ unknown.\ Af=p\ is\ underdetermined $$ x is minimized when abs(f) is ...
1
vote
0answers
16 views

Error analysis and the Model Problem

In numerical methods for ODE's, the model problem y' = cy where c is complex is regarded as sufficient in performing error analysis for different methods in ...
0
votes
0answers
9 views

Optimization with order constraints on parameters

Are there optimizers where it is possible to specify ordinal ranking of parameters? Assume that I have a function of three parameters $f(\theta_1, \theta_2, \theta_3)$. Are there optimizers such that ...
2
votes
0answers
60 views

Inverse problem with a rank-1 update

I hope you can help me out with this. I have to find the solution x to an inverse system $$ x=A^{-1}b $$ This inverse problem is basically a least square problem with a rank-1 update. $$ ...
0
votes
1answer
29 views

How i can find novel machine learning algorithms? [on hold]

Is there any machine learning algorithm from 2010 to now for classification that is useful and popular.I want to use this learning algorithm for pattern classification.I need a novel method with high ...
0
votes
1answer
57 views

LSA, SVD and the Frobenius norm

In Latent Semantic Analysis one uses the SVD to perform a dimensional reduction of the term-document matrix, via the Eckart-Young theorem. Now, the rank $k$ approximation obtained by E-Y is proven to ...
2
votes
1answer
56 views

I have to solve a large binary programming task. Should I avoid branch and bound?

I have to minimize a linear function with respect to variables u which take values [0,1] The number of variables can exceed 10,000 There are thousands of linear inequality constraints I need a ...
3
votes
3answers
92 views

Efficient solver for a symmetric tridiagonal system where the upper/lower diagonals are offset

I'm looking for an efficient way to solve a symmetric tridiagonal system $Mx = d$, where the upper and lower diagonals of $M$ are offset from the main diagonal by $k$ rows/columns: $$ \begin{bmatrix} ...
1
vote
0answers
21 views

SciDB vs OLAP cube

I am working on good retrieval mechanism for big data systems. I am of view that multidimensional structures could be of great use for aggregations and querying and even i can used them instead of ...
2
votes
0answers
46 views

Beam finite element stiffness matrix from section constitutive matrix

I'm trying to construct the 12 x 12 beam element stiffness matrix from a section constitutive matrix (6 x 6 with shear stiffnesses, axial stiffness, bending stiffnesses and torsional stiffness on the ...
0
votes
1answer
43 views

Elastic LP Programming

Say I have an LP that is unfeasible and that I want to find the solution that makes it feasible without strongly violating the current constraints. What is a principled way of solving this problem, ...
1
vote
1answer
35 views

What is Precision-Recall Curve? [closed]

I have a data mining assignment where I make a content-based image retrieval system. I have 20 images of 5 animals. So in total 100 images. My code returns the 10 most relevant images to an input ...
0
votes
0answers
33 views

How to measure the computational costs of solving CSPs and optimization problems?

I would like to define an abstract cost (machine and implementation independent measure) of the work needed to solve CSPs as a function of constraint and Jacobian evaluation counts. I am trying to ...
1
vote
0answers
43 views

Lanczos algorithm with thick restart on a dynamic matrix

According to a recommendation, this is a re-post of that. currently, I'm working on a way to compute the 2 biggest eigenvalues of a real, symmetric, huge and sparse matrix that changes a few entries ...
1
vote
1answer
42 views

oSVD and cSVD terms

In one article I faced with such terms as sSVD, cSVD and oSVD. As I understand sSVD - standart SVD, cSVD - svd for block-circulant matrices, but I can't find what is oSVD. 1) What is oSVD? 2) Can ...
1
vote
1answer
38 views

Is there a reference/source paper for the TUCKER_ALS() in Tensor Toolbox for MATLAB?

TUCKER_ALS computes the best rank-(R1,R2,..,Rn) approximation of tensor X, according to the specified dimensions. I am using MATLAB Tensor Toolbox Version 2.5. I am wondering if I write a paper, how ...
0
votes
0answers
39 views

Computational Science Masters programs [closed]

I have been admitted to a few applied math, computational science, and scientific computing masters programs and am having trouble deciding where to attend. I was admitted to Georgia Tech, UPenn, NYU, ...
1
vote
2answers
79 views

Dense distributed matrix

A dense matrix is distributed for parallel computation column-wise, then multiplied from left & right by sparse matrices. What would be appropriate c++ libraries for these tasks?
1
vote
2answers
175 views

Interpolation by Solving a Minimization Problem (Optimization)

I will try to give the motivation behind this problem and later the math formality. Given a grayscale image (1 Channel - M by N Matrix). Someone marks some pixels as anchors. Now, you need to ...
0
votes
0answers
67 views

How to solve singular non symmetric poisson equation with Neumann boundary condtions?

I am trying to solve 2D Poisson equations with Neumann boundary conditions. When the mesh is uniform, Poisson equation is singular and symmetric, so the method listed in Null Space Projection for ...
1
vote
0answers
77 views

finite volume for diffusion equation with anisotropic (tensor) coefficient

Consider the scalar PDE for $u$ with Dirichlet boundary conditions: $\mathrm{div}(\mathcal{K}\nabla u) = f\; \forall x\; \in \Omega \subset R^2$, $u = 0 \; \forall \; x\;\in \partial\Omega$ ...
0
votes
1answer
34 views

Rank of image intensity matrix

I've been reading a paper about using Matrix Completion for Photometric Stereo but I am having some troubles in section 2.2 trying to understand why irrespective of the number of pixels and the number ...
0
votes
0answers
17 views

Bootstrap for a histogram

I create a set of $T$ trajectories with $P$ positions, $\{x_j\colon 0 \leq j < M\}$, with a Monte Carlo simulation. From this data, I calculate quantities like $\langle x \rangle$ and $\langle x^2 ...
1
vote
5answers
122 views
+50

Algorithm for efficient weighted sampling from a collection that can efficiently be updated

I'm writing a Monte Carlo simulation in which I have to maintain a large collection of items. This collection contains a great many duplicates, and it will most likely be best to store some or all of ...
4
votes
2answers
123 views

Applying matrix square root inverse in matrix-free regime

Let $A$ be a large symmetric positive definite matrix, and suppose that we can efficiently apply $A$ and have a fast solver to apply $A^{-1}$, but we do not have access to the matrix entries for ...
0
votes
0answers
32 views

How to code on matlab for nonlinear systems?

How to code on matlab to solve arbitrary(not polynomial)nonlinear multivariable system of equations?like equations tagged under nonlinear systems of equation(see my equation I tagged)
0
votes
2answers
114 views

Systems of nonlinear equations

Consider the nonlinear system of equations $$ (1) \quad qk^2a_1^2E^2+wna_0a_1AE+pnka_0^2a_1E+rn^2a_0^2A^2-rn^2a_0^3A^2+qk^2a_0a_1ABE-qk^2na_0^2E^2=0, $$ $$ (2) \quad ...
0
votes
0answers
17 views

Keplerian Orbit Estimator

While calculating the eccentric anomaly of a satellite using the Newton-Raphson method, what initial estimate of the root for E (eccentric anomaly) should be taken for least number of iterations(best ...
0
votes
0answers
14 views

Finding eigenvalues of a Hermitian matrix using “eigsh” function from scipy

I am trying to use the scipy.linalg.sparse.eigsh function of scipy to find eigevalues of a Hermitian matrix. In the link below it says that eigsh can handle Hermitian matrices but when I run it gives ...
1
vote
1answer
81 views

Angular Velocity by Vector - 2D

This is originally a problem in programming, but since almost no one on Stackoverflow know how to solve this I went here instead; ...
0
votes
1answer
27 views

Angular Velocity by Vector - 2D [duplicate]

This is originally a problem in programming, but since almost no one on Stackoverflow know how to solve this I went here instead; ...
0
votes
2answers
68 views

WENO reconstruction of flux involving derivative terms

I have a set of modified compressible Euler equations that I would like to solve using a WENO method. The issue is that the modified flux function involves derivative and filtering terms and I'm not ...
1
vote
3answers
70 views

Fast way to compute integral of type $\int dx f(x) \cos(n \pi x)$ in SciPy

I have an integral of the form $$ I(n) = \int_0^1 dx f(x) \cos(n \pi x) , $$ where $n$ is an integer. In other words, I calculate the cosine Fourier coefficients of function $f$, which is real and ...
0
votes
0answers
14 views

Dimensioning in ANSYS design modeler

Say I have two parts with dimensions H50 and H51. I want to make H51 always equal to 1.5 H50 so that I only have to change H50, not H51 each time I run a new model. I tried to put H50 into the value ...
0
votes
0answers
16 views

Conceptual questions on Hopfield network and Particle Swarm

In continuation to http://stackoverflow.com/questions/22768493/neuralnetwork-activation-function/22918658?noredirect=1#22918658. I am using Hopfield network to recognize 3 characters = 0,1,2. I am ...
1
vote
2answers
134 views

Newton-Raphson method fails!

I am trying to solve an equation like $R(x) = 0$, using Newton-Raphson method. To obtain the $x$ increment in each iteration I solve $dx = -(A)^{-1}\cdot R$ where $A = dR/dx$. But the convergence ...
3
votes
2answers
136 views

Methods for solving linear systems

This is such a basic topic but there are so many different methods proposed for solving a linear system of equations. I recently found a very good source but couldn't really make sense of all the ...

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