A description of the specific steps needed to solve a particular problem in an unambiguous way, expressed in an abstract form.

learn more… | top users | synonyms

0
votes
1answer
31 views

Optimizing multiple output parameters for a given input

Problem statement: I'm trying to solve a problem statement using C# as programming language. In the problem system for an input (double/decimal) say $H_i$, the output generated is a form of dataset ...
0
votes
0answers
16 views

Markov (Chain) image generators?

Markov Chains can be used to generate, or auto-complete, text. https://en.wikipedia.org/wiki/Markov_chain#Markov_text_generators Training text is read, and some information about the text is ...
2
votes
1answer
47 views

Help understanding and implementing fast multipole method for N-body

I've been trying to understand the Fast Multipole Method but not really getting anywhere. It seems like the fastest mainstream N-body simulation algorithm, and I would like to implement it in an ...
7
votes
1answer
77 views

N-body simulation optimisation, looking for name or existing work

during the development of my N-body simulation with visualisation in WebGL, I devised an optimisation, and I'm wondering if it has a name. I find it unlikely that it has never been done before. It ...
1
vote
0answers
30 views

I need to deconvolve the image of a fluorescent bead without the Point Spread Function in MATLAB

I am aware that I could use deconvolution algorithms such as LUCY, Weiner and Blind but I am confused as to how to estimate the PSF (point spread function), which is needed for the LUCY and Weiner ...
1
vote
1answer
105 views

Round-robin pairings: Everybody need to meet everybody

I have the following problem, I have a class of N people and I want them to do stuff by pair, but I want them to do this with everybody but as fast as possible. For N = 4 I got this: ...
1
vote
0answers
56 views

Divide and Conquer division algorithm explained (as used in GMP bignum)

I am trying to understand the divide and conquer division algorithm that is used in the GMP bignum arithmetic library. The code is very optimised and that makes it somewhat hard to understand. the ...
0
votes
1answer
62 views

For finding the track of an object through space(3d) over time, what is the correct slope equation to use in the algorithm?

I am working on a program that tracks a flying object through space and predicts the future position of said object. I was given some equations to use, but some of them do not look right, mainly the ...
1
vote
2answers
48 views

Maintain Uniform Distribution across Subranges

Note: this is a continuation of Generate Random Number outside Bounds. I have a function (thanks to the previous question) with the following prototype which returns an integer in the range $[0,b]$, ...
0
votes
1answer
21 views

Calculating adjacency matrix of platonic solids

I need to devise a algorithm (in Python) that calculates adjacency matrices for the platonic solids. Inputted into the algorythm needs to be the number of polygons meeting at each vertex and the ...
4
votes
2answers
109 views

Generate Random Number outside Bounds:

Say I have a random number generator that generates a number within [0, RAND_MAX], and RAND_MAX < UINT_MAX. How do I ...
5
votes
2answers
93 views

How to read the number of periods of this complicated graph?

I have two data sets that are quasi-periodic. They have the same period and can be seen clearly by eye. For example when $x\in(100,200)$, both of them have about 32 periods. Below is a zoom-in of ...
4
votes
1answer
57 views

Balancing number of points in a 2D grid

In a parallel MPI code, I have load balancing issues. My 2D computational domain is distributed on a 2D MPI Cartesian topology, which leads to equal sized 2D sub-domains per MPI process. However, the ...
3
votes
2answers
122 views

Solving a system of linear equations with only an approximate solution

I have a system of linear equations that is derived partially from experimental data. Theoretically, the system should have a single, exact solution; however, experimental error causes it to not have ...
1
vote
1answer
91 views

Calculate the area and perimeter of a hand-drawn shape

I need to know whether my idea for my final year project could be achieved or not. If its achievable please guide me with the relevant language and other frameworks. The idea I have a piece of paper ...
2
votes
2answers
96 views

How to choose the number of random points in Monte Carlo simulations?

I am struggling with convergence criteria when performing a Monte carlo simulation on a uniform distribution. Any help would be much appreciated ! Say I want to sample uniformly a 1D interval (for ...
0
votes
0answers
52 views

How do I remove ripples from a reflected image - as in a pond?

If I have a photograph of a reflection in a pond. How do I recover the image reflected? I've attached an example. What would I need to do to recover the bridge that it reflects? I'm full aware that ...
0
votes
0answers
10 views

ROC curve x axis won't reach 1

I am trying to evaluate a classifcation approach based on thresholds, the idea being that whenever a probability of an observation falls into a certain interval, it is considered a success. I have ...
1
vote
1answer
27 views

Algorithm to Compute Separatrix of Nonlinear ODE

The solution space of a nonlinear ordinary differential equation (ODE) often includes a separatrix that is unstable in the sense that nearby solutions depart exponentially from it. The nonlinear ...
1
vote
2answers
85 views

Traveling Salesman Problem

First off some context. The Traveling Salesman Problem(TSP) is to find the most efficient route passing through a series of points only once. However, there is no perfect function to solve for this in ...
0
votes
0answers
48 views

Algorithms to compute the T-coloring of a graph

The T-coloring of a graph assigns to each vertex of a graph an integer ("color") such that the absolute value of the difference between two colors of adjacent vertices (i.e., connected by an edge) ...
3
votes
1answer
72 views

Fast algorithm for computing matrix square root using randomized linear algebra?

Is there a fast algorithm for computing the matrix square root of a real symmetric matrix using random matrices or randomized algorithms?
2
votes
1answer
227 views

Difference between Gauss-Newton method and quasi-Newton method for optimization

Can anybody help me? I heard that Gauss-Newton method compute an aproximation of the Hessian instead of the true Hessian, but, quasi-Newton method too, don't it? what is the differences between them? ...
2
votes
2answers
151 views

How to implement adaptive mesh refinement using conformal triangles

I am trying to implement adaptive mesh refinement for a finite element code. The code uses (at least for now) linear triangles and so when I do the mesh refinement I want the triangular mesh to remain ...
2
votes
0answers
51 views

Matching/Assignment Problem

I'm not sure how I can represent and solve the following problem. I have a list of sales (timestamp and quantity) and a list of corresponding inventory draws (timestamp and quantity). What I ...
1
vote
0answers
43 views

Time dependent self-consistent equations

I am facing the following problem. I need to solve numerically a set of coupled equations $$i\frac{d}{dt}f_{n}^{(i)}(t) = \left[U\cdot n(n-1) + \mu\cdot n\right]f_{n}^{(i)}(t) - ...
2
votes
1answer
63 views

Parameter reduction algorithm for least square model

Question I am performing least squares fitting using an objective function of the form $f(\mathbf{x})$ where $\mathbf{x}$ is a vector of parameters containing around 20 elements. The model function ...
1
vote
2answers
139 views

QR decomposition

I have a matrix which is "almost" like an upper triangular just that the last row has non zero elements. And I want to perform the QR decomposition on that matrix. Does anyone know the "name" of such ...
2
votes
2answers
118 views

Generation of random Matrix with Real eigen values

does anyone know any matlab algorithm that can help me generate a random matrix with REAL EIGEN values? Thanks.
0
votes
0answers
30 views

Displacement response on the boundary for isotropic elascticity

Let $\Omega$ be a smooth domaine of $\Re^{3}$ and $\Sigma$ a surface of $\Re^{3}$ smooth enouth but not necessarly simply connected (cracks). weconsider the following elastostatic problem(P): ...
1
vote
1answer
60 views

Algorithm for generating the next m-tuple of integers, subject to constraints

I am looking for an algorithm with the following characteristics: It is used to generate the set of integer vectors $\mathbf k=(k_1,\ldots,k_m)$, where $k_i\leq K_i$, $k_i\geq 0$, and $K_i$ are ...
3
votes
1answer
374 views

Efficiency of an algorithm

I designed an algorithm to find the global minimum of a function and implemented it in MATLAB. And I also implemented the "Tunneling algorithm" for the global minimum of a function in MATLAB. But ...
1
vote
0answers
39 views

Area of convex n-dimensional polytope

I am looking for an efficient algorithm to calculate the surface area of an irregular N-dimensional polytope. I have a description of this polytope both as coordinates of the vertices as as linear ...
1
vote
0answers
48 views

Jacobi method converging then diverging

I am working to solve Poisson's equation in 2D axisymmetric cylindrical coordinates using the Jacobi method. The $L^2$ norm decreases from $\sim 10^3$ on the first iteration (I have a really bad ...
1
vote
0answers
32 views

similarity/distance measurement between two ranked sequence

Is there an efficient way to measure similarity/distance between two sequences of ranked numbers/letters. The two sequences are of different length, and only have some elements in common? For ...
1
vote
0answers
39 views

Manipulating/Extracting Data and Developing Methods - Language Choice [closed]

As a general programming enthusiast and aspiring Bioinformatician student I have an intermediate understanding of computing (languages) as well as Java, and to a lesser extent C++. Having knowledge in ...
1
vote
1answer
101 views

Algorithms for one-to-many assignment problem

I'm looking for a computationally efficient algorithm for solving the following type of assignment problem: I have two sets of points. Set A has N points and set B has M points. I'd like to establish ...
2
votes
1answer
148 views

Comparison of convex hulls [closed]

Consider a set of polytopes $P_i : i=1,2,...,k$ each of which has a structure as $P_i:= \{(x_{i1},x_{i2},..., x_{in})\; |\; x_{ij} \in [a_{ij}, b_{ij}] \subseteq [0,1]\}\;\; \text{for all}\;\; ...
0
votes
0answers
33 views

“Tunneling” optimization algorithm in Matlab

I was wondering if someone has implemented the "Tunneling algorithm" for the global minimization of a single variable function in Matlab. I am hoping to implement it on $[B, A - \lambda I]$. Where ...
1
vote
1answer
30 views

When we compute the complexity of a given algorithm related to image processing does the N refers to the number of Pixels in the image?

When we compute the complexity of an image processing algorithm, we get an $O(N)$. does the $N$ refers to the number of pixels in the image or to the height/width of the image, I mean it is computed ...
2
votes
2answers
296 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 ...
1
vote
1answer
84 views

Fast algorithms for computing only the generalized singular values (but not the vectors)

I am interested in computing only the generalized singular values, and was wondering if this was faster (and by how much?) than computing the full GSVD. In particular, I was wondering what the ...
0
votes
1answer
63 views

Is this the correct procedure for calculating matrix spectrum?

I am not sure if my question is on topic but I have a piece of Fortran code that is used to perform successive over relaxation. Prior to performing successive over relaxation the author is calculating ...
2
votes
1answer
38 views

Simple Path to Route Algorithm

I'm currently conducting research into subway paths, but stand in front of a problem, with no programming knowledge and an extremely short time-limit. Probably the question I am asking is trivial, ...
0
votes
2answers
104 views

Looking for a particular algorithm for numerical integration

Consider the following differential equation \begin{equation} p(t) = \frac{\partial q(t)}{\partial t} \end{equation} where $t \in (0,\infty)$. I have a build a code that spits out values of the ...
1
vote
0answers
120 views

General algorithm to solve systems of symbolic equations

I want to simplify (solve) a system of linear + nonlinear symbolic equations as much as possible. the equations are of random orders, without differentiation. is there a general & well-known ...
1
vote
2answers
196 views

Ideas on how to search nearby geospatial data fast

I am looking at a very simple problem, but can't quite find the best solution. I need to accept a lat/lon coordinate and based on that coordinate find all the points within roughly ~1km (accuracy is ...
9
votes
2answers
185 views

How does weak convergence feel, numerically?

Consider, you have a problem in an infinite dimensional Hilbert or Banach space (think of a PDE or an optimization problem in such a space) and you have an algorithm that converges weakly to a ...
2
votes
1answer
115 views

Does this “reverse binary search” have a name?

Normally when searching in sorted sets, binary searches are a fast, nice and easy way to locate data. It does however break down in the hypothetical scenario of having a set of arbitrarily large but ...
-1
votes
1answer
74 views

Is iteration an efficient algorithm in this case? [closed]

My task in numerical analysis is We are interested in finding values of β0 for which z(x) = 2500. Use an efficient algorithm to determine the rays which pass through the receiver. Now I'm ...