# All Questions

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393 views

### Why my linear congruential generator generate low quality random numbers?

I am implementing an arbitrary bits random number generator (in [$0,2^n$)) and also want to ensure that the generator always generate unique numbers until all possible numbers generated, so I ...
432 views

### Best platform for complex SDPs with n and m around 5-15K?

I am looking to solve a class of SDPs with complex entries, with the semi-definite cone $S^n$, $n$ around 5000 to 15000. Also, $m$, the number of equality/inequality constraints is close to $n$. I ...
76 views

### trilinear hex elements

Do the faces of tri-linear hex elements have to be planar? Three nodes define a plane. If the fourth node does not lie on the plane, then the nodes are not planar and the face is not plane. In general,...
221 views

### Solving a nonlinear equation with random variable

I would like to solve an equation that looks like this UPDATE $E[(R^{1-\gamma})(r_k+\theta-r_z)]=0$ , where $R=\phi r_z+(1-\phi)(r_k+\theta)$ and $\phi\in[0,1]$, $\theta$, is a random variable ...
2k views

### Numerical solution of non-linear diffusion equation via finite-difference with the Crank-Nicolson method

I want to numerically solve the non-linear diffusion equation: $$\frac{\partial}{\partial t} T(x,t)= \frac{\partial}{\partial x}\left(T^{5/2} \frac{\partial T}{\partial x} \right)$$ I want to use ...
1k views

### Computational complexity and implementation of UDU Modified Cholesky Rank 1 Update

I am attempting to increase the performance of a legacy Kalman Filter implementation. The state covariance is factored in terms of UDU, i.e. $\mathbf{P} = \mathbf{U}\mathbf{D}\mathbf{U}^T$. Many ...
134 views

### Algorithms to generate spherical codes

A spherical code, specified by the parameters $(n,N,t)$, is a set of $N$ coordinates on the $n$-dimensional unit hypersphere such that the set of dot products between any two unit vectors from the ...
5k views

### Creating 3D Mesh from stl files with gmsh

After long hours of searching for an answer I thought it might be better to ask the community. The problem I have is that I need to convert STL files to mesh files. I know that I therefore need to ...
259 views

### Multigrid stops converging when more grid levels are used

I'm having a problem with multigrid code I wrote. If I solve Laplace's equation in 2D and use more than 5 grid levels, the V-cycles stop converging after a few cycles (see below, convergence factor > ...
394 views

56 views

### Shall I use global, heap allocated array or local, stack allocated one if references to its elements are made too many times?

I actually have this data locality as a possible problem for why my fortran program runs somewhat slow. In one part of this program, I have nested loops and throughout these loops, a given section of ...
241 views

### What numerical methods are used to model deformations in elastic physics?

What numerical methods are used to model deformations in elastic physics? For example, here's an example of a hyperelastic deformation in Ansys: Perhaps more simply than hyperelasticity, for linear ...
125 views

### Quick way to find a common basis of eigenvectors between 2 matrices : valid or not?

Following the advise of @Federico Polonion a previous post, one suggested, to find a basis of common eigen vectors between 2 matrices, to simply do : Generate 2 ...
301 views

3k views

### Solving Advection (Convection) - Diffusion - Reaction Partial Differential Equation in Python

I am looking for library written in Python which will enable me to solve the coupled nonlinear equations which looks like: I need the library which will enable me to couple this solver to other ...
3k views

### C++ Library: What is the common libraries that do polynomial arithmetic?

I need to know what libraries (in C++) support polynomial arithmetic specially over a field. So I can give to it an array of coefficients of polynomial over a field and it returns the roots of ...
2k views

### What is the difference between “Newton-type” and “Newton-like” iteration?

Is there any clear classification between different iterative methods? What is the difference between Newton-type and ...