# Questions tagged [algorithms]

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

447 questions
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### “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 $A$...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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, ...
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### Looking for a particular algorithm for numerical integration

Consider the following differential equation $$p(t) = \frac{\partial q(t)}{\partial t}$$ where $t \in (0,\infty)$. I have a build a code that spits out values of the ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 just ...
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### website for algorithm analysis in various languages

Not sure if this is the right place to post this, but some time ago i stumbled upon a website which had algorithms submitted by users in different languages... I am unalbe to find that website, anyone ...
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### extract exhaustive mutually exclusive intervals from larger set of intervals [closed]

I have a collection of time intervals with integer valued endpoints , e.g. (1,2), (2, 6) (5,6), and the number of events falling in each time interval, and I would like to determine if from them I ...
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### Enumerating set combinations in an order that maximises the number of previously unseen subsets

Consider a set $S=\{a,b,c,d,e,f,g,h,i,j,k\}$, $\left|S\right|=11$. There are ${11 \choose 5} = 462$ combinations of $S$'s members of size $5$. There are $462! \approx 1.419 × 10^{1032}$ possible ...
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### Should a randomly-seeded genetic algorithm give deterministic optimized solutions on each run?

I am going to rewrite an algorithm using genetic methods for mutating my solutions, and I am wondering what I should expect and only consider my algorithm "optimized" or "finished" if various runs of ...
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### What is the fastest algorithm for computing the inverse matrix and its determinant for positive definite symmetric matrices?

Given a positive definite symmetric matrix, what is the fastest algorithm for computing the inverse matrix and its determinant? For problems I am interested in, the matrix dimension is 30 or less. ...
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### Determining if samples fit a 3D Gaussian distribution

I have a collection of sample particles, with (x,y,z) coordinates generated by a simplified Monte Carlo-like code. I expect that these particles will follow an anisotropic diffusion process, which ...
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### Optimization of nonlocal stencil-like operator on subset of regular grid

I am trying to optimize the execution time for this particular piece of fortran code. Details: i_gc is a (ngpts, 3) array of containing (i,j,k) indices for each grid point. This is a subset of the ...
I have the following problem. I have two sequences of elements $A = [a_1,a_2,\cdots,a_n]$ and $B = [b_1,b_2,\cdots,b_m]$. I can build a matrix $D[n \times m]$ where $d_{ij} = d(a_i,b_j)$ My greedy ...