# All Questions

43 views

### Are there any possible applications of real-time Finite Element Analysis?

FEA when applied to solid mechanics / structural engineering result in the solution to the equation $$F = K\cdot x$$ $F$ being the forces, $K$ the stiffness of the system and $x$ represents the ...
15 views

27 views

### Anyone need expert help/consulting with advanced programming languages? [on hold]

Code Genius was started at MIT to connect programmers in the scientific community to experts of advanced languages for efficient and cost effective support. Our platform helps programmers find the ...
23 views

### Min/Max Depth of a binary tree [on hold]

Is the Min Depth of this tree 2, because of the distance of leaf node "9"? Is the Max Depth if this tree 4, because of the distance of leaf node "2"?
63 views

### Dissipative time-stepping scheme for first order in time system

When solving semi-discrete equations (originating from finite element models, for example), which are second-order in time of the form $$M\ddot d + C\dot d + Kd = F,$$ ...
67 views

### Generating random numbers for long molecular dynamics simulations

I've written a basic 2D Langevin dynamics simulator in C++, for a particle in a potential, solving the equation: $$M\ddot{X} = - \nabla U(X) - \gamma M \dot{X} + \sqrt{2 \gamma k_B T M} R(t)$$ This ...
80 views

### Relation between Time dependent problem and advection diffusion

Is there a relation between say the heat equation $u_t -\Delta u = f.$ and advection-diffusion equation $-\Delta u + c \cdot \nabla u = f$? I have heard several people use this argument in many talks ...
36 views

### Calculating theoretical order of accuracy of least squares fit advection scheme

I'm familiar with finding the order of accuracy using von Neumann analysis for finite difference schemes formulated using Taylor series expansions. But is there a similar technique for finding the ...
59 views

### Are there any standardized file formats for point group character tables?

Character tables are an important tool for symmetry analysis in many computational chemistry software packages. Are there any standardized file formats for point group character tables? This may seem ...
51 views

### transverse component for multidimensional advection in method of lines

So I inherited from some people a code that solves the advection-diffusion-reaction equation for a particular system. The original code was first implemented in 1D which worked fine in cartesian ...
27 views

### fixed point iteration to find out second order non-linear diff equations

I am working on some model analysis, getting two diff equations and after I convert them into matrix form, I have equations looks like $$[A][X]=C\times\big(\exp([B][X])-1\big),$$ where $C$ is a ...
54 views

### Efficient method to multiply floating point matrix with binary matrix and get double precision results

I have a matrix A which is of size (n2, n1) and I am multiplying it by a matrix, B, of size ...
17 views

(First off, a disclaimer: I'm new to the site, and not quite sure this is the proper forum for this question. My apologies if it's out of place). I'm working on a computational algebra project and ...
13 views

### GAMS AND C++ CONNECTION [on hold]

I wrote a optimization model in GAMS and I want to solve the same model with about 100 different data. Instead of inputting the data one by one by hand, I need to do it with a for loop on C++. Is it ...
55 views

### minimization of normalized constrained quadratic function

I'm a computer science student. Please I need a help in solving a constrained normalized quadratic function. I'm familiar with solving quadratic constrained optimization function with matlab by ...
46 views

### Creating a 3D spatial density map from simulation results

I want so visualize the spatial density for my simulation. The result of my simulation is a (time-dependent) system of large number (~100k) of moving particles in a confined space. Each particle has ...
89 views

### How to calculate $det(X^TX)$ efficiently, update one column of X each time

$X_{1} = (A, b)$, where $X_{1}$ is a $n\times p$ matrix, $A$ is a $n\times (p-1)$ and $b$ is $n\times1$. First calculate $\det(X_{1}^T X_{1})$, then update $b$ with $c$, st. $X_{2} = (A, c)$ and ...
51 views

### Numerical Solution of the Advection Dispersion equation

I am facing a simple (at first glance) problem. I need to implement a numerical scheme for the solution of the first order wave propagation equation with chromatic dispersion included. My original ...
166 views

461 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, ...
56 views

### Solving quasilinear/nonlinear equations obtained from the discretization of partial differential equations

When you solve numerically a (system of) linear partial differential equation (PDE) as for example Lapace's equation $\nabla^2\varphi = 0$ or Poisson's equation $\nabla^2\varphi = f$ you obtain a ...
27 views

### Fortran solver for the Sparse LSE problem

I was wondering if there is a Fortran library that contains a solver for the Sparse LSE(linear equality-constrained least squares) problem $$min_{x}\|Cx-d\|^2 \text{ subject to } Ax=b$$ where $A$ ...
28 views

### How to represent a binary number in a matrix in Matlab?

This is a fairly simple question but my Matlab knowledge is still very limited. I want to take a given binary number (or rather, a bistring) of length $mn$ and generate an $m \times n$ matrix whose ...
44 views

### Is there an efficient $O(n^2)$ way to get the eigen decomposition given a LDL factorization?

Let's say I have a LDL factorization of a matrix A. Is there an efficient $O(n^2)$ way to get the eigen decomposition of A given it's LDL factorization? Is there a more efficient way, in case L and ...