# Questions tagged [multigrid]

Questions about multigrid methods for numerically solving differential equations.

27 questions
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1answer
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### - Optimization - Standard Grid Search

I'm struck into an portfolio opt. problem and the paper I'm replicating (or, better, trying to) is using a "Standard Grid Search". Since I never encountered it before, I would like to ask you about: ...
1answer
28 views

### Number of rectangle of size x,y which cover a cell p,q

I have a rectangle of size n*m (Where n is a number of rows and m is the number of columns) which is divided into of size 1*1. I want to calculate the number of the rectangle of size P*Q which ...
0answers
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### What does “smooth” mean? (Numerical Analysis)

I know a notion of smoothness for functions, say, in $\mathbb{R}^n$, which simply means of class $C^\infty$. But in studying Numerical Analysis I sometimes read the term smooth for discrete functions, ...
0answers
78 views

### Is the application of the multigrid method correct?

We consider the boundary problem \begin{align*}-&y''(x)=0 \ \ \text{ for } \ x\in \Omega:=(0,\pi) \\ &y(0)=y(\pi)=0\end{align*} Let's pick the grid size $n=5$. I want to apply the 2-grid ...
0answers
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### effect of relaxation factor for Jacobi smoother in multigrid solver

I've been reading about multigrid solvers and they mention that using Jacobi as a smoother with a relaxation factor can have a difference in the performance of the algorithm. I never really understood ...
0answers
42 views

### ADMM Heuristic or rather stick to Branch and Bound?

I'm intending on giving a solution to this MIQP, which should be faster than the one of solving the exact problem with GUROBI or CPLEX.(It muss not give always the global solution!) The main ...
1answer
194 views

### How many ways can blocks be arranged in a grid

I have a 16x16 grid to fill up with 4 different sized blocks listed below: 16x16 16x8 8x16 8x8 How many different combinations of 16x16 grids can I make while filing the grid up completely? Just to ...
2answers
45 views

### Looks like a magic square, but can't solve it, please help.

A friend sent me this from her game I tried many combinations and I cannot solve it for the life of me. 9 squares starting from each corner is (top left 61, top right 61, bottom left 69, bottom ...
1answer
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### Finding the value of a point in 3D domain depending on neighboring points

I have some data on 3D models of soil's moisture content, the model is in the finite-element grid. I have converted the program outputs to a table in four columns x, y, z, Theta where Theta is the ...
0answers
55 views

### Can L, the square lattice on the plane, be partitioned into finitely many subsets that (up to translation) are contained in a rotated version of L?

I ran into this interesting problem while thinking about some stats models the other day. The context was efficient estimation of anisotropic covariance structures in geostatistical models, but it ...
0answers
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### Addressing/traversing an infinite 2D grid using a Z-line?

I'm looking for a method to map an infinite 2D grid using a line, so that I would have just one integer from which I would compute the X and Y. I know something like that exists, but can't recall the ...
1answer
454 views

### Multigrid tutorial/book

I was reading Press et. al., "Numerical Recipes" book, which contain section about multigrid method for numerically solving boundary value problems. However, the chapter is quite brief and I would ...