# Questions tagged [grid]

The tag has no usage guidance.

45 questions
Filter by
Sorted by
Tagged with
10k views

### Dynamically ending ODE integration in SciPy

I have a light ray moving through space-time, i.e. a curve in $\mathbb{R}^4$, parametrized by some variable λ. The exact trajectory, i.e. the coordinate functions $x^μ(λ)$ of the curve are given by ...
127 views

### What makes a good computational grid?

Most computational methods for solving PDEs are grid-based. What makes a computational grid "good", other than being sufficiently fine to resolve features of numerical solutions? Are grids ...
170 views

### How to optimally choose points for multivariable Hermite interpolation?

I have a multi-variate, continuous function $f$ from $R^n$ to $R$, which I can query for its output for any input. I would like to create interpolation polynomial for it. In one-dimensional case ...
2k views

### Python: Grid with step control ODE solver

I have a problem in physics formulated via an ODE. Now I like to solve it numerically using Pythons scipy.integrate and the therein complex_ode. I figured out how and it works but now I like to ...
1k views

### Generating a non-uniform grid

I am interested in generating a 1D non-uniform grid on the interval [0, L] with N points, where a region of width $\sigma$ and ...
126 views

### Alternative to messy grid node indexing within multiple layers of loops

Recently,I dive into a set of somehow ancient Fortran codes and try to fully understand them. A large fraction of these codes are multiple layers of loops over many state variable dimensions, which ...
82 views

### What is the reason for this finite-difference high errors on non-uniform grid?

tl;dr Using a Taylor-matched method to find coefficients for the discretized equation $\mathbf{A} \vec{f}'' = \mathbf{B} \vec{f}$, a Fortran code has been implemented to find the second derivative ...
114 views

86 views

### Common nodes in two FEM grids

There are two independent tetrahedral FEM grids. Second grid is subset of the first. By subset, I mean: nodes from the second grid are exactly in the same positions as some nodes from the first grid. ...
94 views

150 views

### C1 continuous spline on regular 2D-grid with quadratic 1D cuts

I want some scalar spline function defined on regular 2D grid $F(x,y)$ with continuous first derivative which is easy to intersect with arbitrary ray/line ${\vec l}(t) = (c_x t,c_y t,c_z t)$. ...
132 views

### Finding boundary intersection points with Cartesian grid?

I would like to find the intersection points e.g. $M_x$ and $M_y$ as in the attached figure. The boundary (solid line) is defined by the Lagrangian points. I am working in C++ (basic - medium ...
293 views

### Ray tracer : create an uniform grid [closed]

I wrote a simple ray tracer, and now I try to implement an uniform grid. There is a lot of documentation on how to traverse the grid, but I don't know how to construct the grid. I have my uniform ...
65 views

### Grid Independence Study

Is the change in time step necessary for the grid independent study? As the CFL is based on the relation between dt and dx. In mesh independent study, only change should be mesh i.e, dx isn't it so?
51 views

### Cells segregation

There is unstructured grid which contains only quadrangles cells. Each cell has 4 neighbors, and known them (has a pointer to them). I can iterate through all cells in the grid. Some cells are marked ...
39 views

### Converting mass density to point mass approximation on a grid

In an nbody gravity simulation, instead of doing exact(all-pair brute force) solution, I added masses of each body into cells of a 3D grid(each cell is just a float value having a mass value). Then ...
959 views

I would like to code for a quadtree type meshing but don't know how to do. If anyone can help or can share any starting code?
62 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 ...
132 views

### Good C, C++ library for efficient grid search / tuples, ideally with bindings to Eigen

I have a $q$-dimensional grid, known at run, not compile-time, that has $50$ points in each direction and hence $50^3$ combinations that I would like to first build and then call a function with each ...
50 views

### Balancing core load when number of particles in cells vary (PIC on GPU)

Consider this basic scheme for particle in cell simulations ( with just short-range interactions ): assign particles to disjunct cells for cell $A$ go over neighboring cells $B$ for each particle \$...
15 views

### A way to generate unit lattices from a honeycomb structure

I am looking to make certain computations on the vertices of periodic cubic honeycombs and quasiregular honeycombs like tetrahedral-octahedral honeycomb. Cubic are simple enough and amount to generate ...