Questions tagged [algorithm]
Questions about algorithms used or which might be used to implement a procedure known by name or loosely but not in detail. The subject of the question may be a procedure mentioned in the literature or a Mathematica built-in function
286
questions
1
vote
2answers
51 views
Mistake in recursive algorithm
I am new to Wolfram, and I am trying to make a recursive Archimedes algorithm in Wolfram.
I read documentation and I tried to run this code
...
0
votes
0answers
18 views
2
votes
0answers
106 views
Combinatorics with booleans equations
I have variables $X_i \in \{1,0,-1\}$. Now I add up $m=3$ variables
$$S=X_1 + X_2 + X_3
$$
and want to find all combinations that give me, $S=1$. I can do this with (see this solution):
...
3
votes
0answers
60 views
Steiner Tree Approximation
I am wondering about the existence of Mathematica code to find (approximate) Steiner trees in graphs. I know there are a number of algorithms to do so --- just curious if anyone has implemented any ...
3
votes
1answer
74 views
Sorting a list into “all possible ways” - sorting with incomplete information
Familiar example of sorting objects
I have a list of $n$ "vectors" $\{x^{(1)},...,x^{(n)}\}$ of form $
x^{(i)}=\sum_{j=1}^m c_j^{(i)}x_j,i=1\dots n$, where $c_j^{(i)}$ are
nonnegative ...
6
votes
0answers
76 views
Mathematica's algorithm for FindIndependentEdgeSet? [closed]
Documentation does not mention about algorithm. My guess is Blossom algorithm because I do not know of any better one.
Posting it with hope that someone might know it for sure.
2
votes
1answer
37 views
Creating pairs of non-intersecting set from a given set
Let's say I have a set {a,b,c,d} and I want to create a list of pairs {{a,b,c,d},{}},{{a,b,c},{d}},{{a,b,c},{}},... such that there is no intersection between each pair, and they do not need to use ...
1
vote
0answers
43 views
How does Mathematica find the process parameter? [closed]
I want to know what kind of algorithm is used by Mathematica's Estimated Process.
For example, we can estimate the parameter as follows:
...
1
vote
1answer
93 views
Given a function $f(t,s)$, compute $\max_{t_2\in [0,1]}\min_{t_1\in [0,1]} |f(t_1,s_1)-f(t_2,s_2)|$
Given a continuous and bounded function $f(t,s)$, $t,s\in[0,1]$, I would like to compute
$$\max_{t_2\in [0,1]}\min_{t_1\in [0,1]} |f(t_1,s_1)-f(t_2,s_2)|,$$
for each numeric values of $s_1$ and $s_2$....
2
votes
1answer
60 views
Find critical radius in percolation
I would like to examine the percolation from the left edge to the right edge on random lattice.
Suppose I have a rectangle with N random points on it.
...
2
votes
1answer
48 views
What would be the best implementation of the D'Hondt method of highest averages for allocating seats on party-list proportional representation?
The 2019 European Parliament elections are happening shortly and seat allocation will use the D'Hondt method of highest averages. In order to analyse possible scenarios and results I need a Wolfram ...
1
vote
1answer
64 views
Duplicate RowReduce
Writing:
Ab = {{1, 2, 3, 4, 2},
{4, 3, 5, 6, 3},
{1, 6, 7, 8, 4},
{9, 1, 2, 3, 2}};
RowReduce[Ab]
I get:
{{1, 0, 0, 0, 1/16},
{0, 1, 0,...
0
votes
0answers
50 views
How to exclude some methods?
Can I exclude one or several methods from methods tried by a function?
When we use some 'algorithm-intensive' function, we can often specify whether we want to proceed according to the chosen method ...
3
votes
2answers
1k views
The most efficient algorithm to find all possible integer pairs which sum to a given integer
I wrote a module in Mathematica which finds all possible pairs of integers from a specified list of integers (which can be negative, zero, or positive) which sum to a specified integer m.
The only ...
12
votes
2answers
844 views
Solving “Resistance between two nodes on a grid” problem in Mathematica
In the context of resistor networks and finding the (equivalent) resistance between two arbitrary nodes, I am trying to learn how to write
a generic approach in Mathematica, generic as in an approach ...
0
votes
0answers
64 views
Most efficient way to define evil and odious numbers [duplicate]
A positive integer $n$ is defined to be evil if the number of ones in its binary expansion is even, otherwise it is odious. Now define the function
$$
\begin{equation*}
t(n)=
\begin{cases}
1 \rm{ \...
1
vote
0answers
88 views
How can I improve and accelerate my 2 D algorithm?
I implemented the algorithm descussed here in the 1 D case (when $g$ is one variable function). Using a relaxation parameter the algorithm became very fast and converges in few iterations (n = 5, 6, , ...
5
votes
2answers
296 views
Finding the dangling free part of a cluster connecting two nodes
I am trying to learn how to use Mathematica for analyzing graphs, more specifically in the context of connectivity and percolation.
For the sample graph that I have included in this post, we have a ...
3
votes
0answers
87 views
Approximate Nearest Neighbors in Mathematica?
Is there any support for Approximate Nearest Neighbors (ANN) in Mathematica or third-party packages? I'm looking for a good implementation of locality sensitive hashing for applications where ...
3
votes
0answers
110 views
Hopcroft's Algorithm for Minimization of Deterministic Finite State Automaton
Background
Given a deterministic finite state automaton, Hopcroft's algorithm is a $O(n \log(n))$ algorithm for finding an automaton that generates the same language with a minimal number of vertices....
2
votes
0answers
29 views
How to iterate over Orbit of PermutationGroup?
Another day, another permutation group question.
I'm given a g=PermutationGroup[...], and a list l={1, 3, 3, 2, ...}. I know I ...
1
vote
0answers
101 views
Trying to compute the heat capacity for the 2D-Ising model
I'm trying compute the heat capacity $C_v$ out of my simulation for the 2D-Ising model which is given by
$C_v = \frac{\langle E^2 \rangle - \langle E \rangle^2}{T^2N^2}$ ($E$: Energy, $T$: ...
1
vote
1answer
70 views
Defining iterative algorithms [closed]
Assume the iterative algorithm of interest to be as follows:
...
4
votes
1answer
58 views
Mathematica package to calculate the graph crossing number
I have been searching for a mathematica package that can calculate the graph Crossing number of a (small) given arbitrary graph (the graphdata of known graphs doesn't help me). Before I write my own ...
1
vote
0answers
70 views
How can we make an algorithm with the A* method in Mathematica with 5 different flight routes? [duplicate]
I need to find the shortest path with the A* algorithm using Mathematica.
I have 5 different flight routes with coordinates. They start and end at the same point. Between every point there is a wind ...
2
votes
4answers
144 views
How can I compute the chromatic number of a graph?
I'm starting in Wolfram Mathematica.
I saw that MinimumVertexColoring [g] could be used to calculate the chromatic number of a graph, but ...
3
votes
1answer
120 views
Identify emotions from a drawn face using machine learning?
Can someone tell me how you could modify this code so that it recognizes more facial expressions? ... thanks for the help.
...
6
votes
1answer
471 views
Which algorithm does Mathematica use for “RandomSearch”?
Recently I have used Mathematica for minimization of certain functions and I have realized that even though it lasts much longer, the method "RandomSearch" functions much better than the other methods ...
4
votes
1answer
248 views
Pythagorean quadruples
I am very interested in the problem that deals with the Pythagorean quadrruples, which are listed in rosettacode. Unfortunately, I have not been able to find any way to compute them with Mathematica. ...
7
votes
1answer
366 views
Why is SVM unable to separate linearly separable data?
I have two sets of data, namely blue and yellow. I manually added a point {8, -3} to the blue data.
...
3
votes
0answers
180 views
How to achieve with Mathematica the effect a closure has in other languages?
Motivation
I want to write an auxiliary function (brief auxf) for testing the output of another function that evaluates its body repeatedly using ...
3
votes
1answer
108 views
How to improve the simulation speed?
I'm new here. Actually, Mathematica is so cool, I can just write about 5 lines to do the same thing comparing to over 100 lines in Python. But the speed is very slow. I wonder if there is any method ...
7
votes
2answers
195 views
Generating permutations
I have a list of different combinations of letters of the alphabet
{{"a"}, {"b"}, {"c"}, {"a", "b"}, {"a", "c"}, {"b", "c"}}
There is no pattern to them - that ...
0
votes
2answers
72 views
An Integrate result is not what it should be
Recently, I come across an algorithm called HyperLogLog (https://stackoverflow.com/questions/12327004/how-does-the-hyperloglog-algorithm-work). There's a magic number in it, and when reading the paper,...
10
votes
1answer
208 views
Quick QuickSort implementation
I am playing with julialang and loving it, but at the same time noticed that they have a benchmark comparison with Mathematica. I have already submited a better version of ...
3
votes
1answer
83 views
What algorithm is used by FindGeometricTransform? [closed]
Can anyone tell me how the operation FindGeometricTransform[pts1, pts2] works (I mean inside logic of the transformation function), or where can I find such an ...
5
votes
2answers
136 views
How to mark leaves of polynomial based on its position in tree
I've been struggling with this for a few days, and so I thought I might ask this here. Part of the problem lies in the fact that I do not even know the mathematical solution, which runs the risk of ...
1
vote
1answer
272 views
Find a few eigenvalues of a HUGE sparse Hermitian matrix
I know that methods such as Arnoldi and FEAST can be employed to only find a few eigenvalues. But now I need to add another ...
1
vote
3answers
82 views
0
votes
1answer
265 views
Using the binary search algorithm in a sorted grid
I want to get a mathematica code for binary search algorithm applied to a sorted grid containing integers.
For example, given
f[k_,x_]= x^2 + k x + k - 2
where <...
0
votes
0answers
76 views
What method Mathematica uses to solve a quadratic system
I'am writing a paper and I need to know what method Mathematica uses to solve a quadratic system by default.
This is my system:
...
6
votes
2answers
568 views
How to calculate the “center” point
I have such points
pts = Uncompress[FromCharacterCode[
Flatten[ImageData[Import["http://i.stack.imgur.com/zEP05.png"],"Byte"]]]];
ListPlot[pts]
If I use the ...
3
votes
3answers
2k views
Algorithm too slow
Writing:
nn = 10;
Table[Sum[Length[Select[DeleteDuplicates[Map[Sort, Tuples[
{1, 2, 5, 10}, i]]], Total[#] == n &]], {i, 1, n}], {n, 1, nn}]
I get:
{...
0
votes
0answers
32 views
Using space to denote multiplication [duplicate]
When I want to impress a Mathematica novice I show him how we can use spaces to denote multiplication (telling him also to be careful not to forget the space as in ...
6
votes
2answers
344 views
Improve my implementation of the Diamond square algorithm
Some time ago, I began to explore the magnificent world of the terrain generation using the computer. Investigating on the Internet know about the existence of the diamond square algorithm. Try to ...
5
votes
1answer
189 views
solid partitions generator
According to Wikipedia, a solid partition of $n$ is a three-dimensional array $n_{i,j,k}$ of non-negative integers (with indices $i,j,k \geq 1$) such that $$\sum_{i,j,k} n_{i,j,k}=n$$ and $$n_{i+1,j,k}...
3
votes
1answer
288 views
Metropolis-Hastings Algorithm Problem
I've been trying to implement the Metropolis-Hastings algorithm for a while but there seems to be something weird going on.
This algorithm does not need as much of the statistics to understand, and ...
6
votes
4answers
425 views
How to speed up this high-dimensional definite integral?
Examples
➤ 1.
$$I=\iiint\limits_D \dfrac{{\rm d}x\ \!{\rm d}y\ \!{\rm d}z}{(x+y+z)^p}~,$$
where
$$D=\{~(x,y,z)~\colon~x>0~,y>0~,z>0~,x+y+z<1~\}~.$$
MMA gives: $~I=-\dfrac1{2(p-3)}~.$
➤...
2
votes
2answers
97 views
I want to improve my algorithm of knowing eigenvalues of the matrix H(k)
I want to improve my algorithm.
I want to know the eigenvalues of below n-dimensional matrix H. When n=10, the matrix H is like below.
Now, $To$ and $M$ are constants and $T1$ and $T2$ are functions ...
4
votes
2answers
201 views
Numerical Join of two sets of vectors ignoring repeats
I have two sets of numerical vectors which can be either Real or Complex and I want to combine them together, ignoring repeats.
...
