# Tagged Questions

Questions about random number generation and the properties of numbers so generated.

38 views

### Random bipartite graphs?

RandomGraph[{n,m}] generates a random graph with $n$ vertices and $m$ edges. I want to generate a random bipartite graph, like ...
56 views

### RandomPoint works with a 2D ImplicitRegion but fails for any higher dimension

This is inspired by this answer which features code that I cannot get to work at all, and I tried to figure out why. It boils down to using the function ...
135 views

### Why is Random faster than RandomReal?

As of version 6, Random[] was superseded by RandomReal[ ] etc, but both still work perfectly well. Playing with some timing ...
175 views

### How to generate two group of $n$ random numbers in $U(0,1)$ such that sum of these two groups equal? [on hold]

I want to have two groups of $n$ random numbers $u_i$ and $v_i$ in $U(0,1)$, such that $\sum u_i = \sum v_i$ What I tried is: I can firstly get $u_i$ by ...
67 views

### RandomPoint fails with a large enough number of points

Bug introduced in 10.2.0 and fixed in 10.3.1. RandomPoint is new in 10.2.0. I have defined a simple ellipsoidal parametric region: ...
70 views

### Smooth initial data

I need something that produce pseudorandom smooth initial data for modelling phase separation equations (Cahn-Hilliard and simular). Generator code for now: ...
39 views

### Generate a simulated covariance matrix

I am working on a problem where one of the input variables is the level of covariance between the entries in a particular matrix. To simulate this problem in Mathematica, I will need to feed my code ...
125 views

### Handling of Temporal Data [closed]

I use a random function of a process which yields a Temporal Data object, I need but do not know how to recuperate the numerical values of the process in a Table from the Temporal Data.
115 views

### Confining/Periodic boundary conditions implementation for 2D Random Walker

I am new to Mathematica, and am having trouble implementing confining boundary conditions for a random walk simulation confining the walker to a pre-defined region (periodic boundary conditions would ...
199 views

### What is the fastest way to obtain the eigenvalues of a Wishart matrix?

I would like a fast method of creating a sample of random numbers which corresponds to the eigenvalues of a Wishart matrix: For M>N the eigenvalues \lambda_i are given by the jpd Where $K_N$ is ...
75 views

### Manipulate a random walk [closed]

For a college project I am manipulating a random walk. I managed to make a walk but in the manipulation every time a step is added the manipulation shows an entirely different walk. I understand why ...
109 views

64 views

### Generate $n$ randomly oriented non-intersecting cylinders with fixed radius and length

This post is in reference to the previous question here. How could I adapt the solution given to have the following constraints: fixed radius, fixed length, number of cylinders, and within a ...
2k views

### Random letters: What is the chance that real words are generated?

Suppose that we are just typing random letters with our keyboards and we include space bar. We don't distinguish between capital and lowercase letters. If we do this for a long time, how many of the ...
205 views

### generating randomly oriented non-intersecting cylinders

I could not find anything relevant with "googling" (only this) I can create a set of randomly oriented cylinders (code found here) ...
95 views

### ParallelTable and Random

Each time I execute the following code it generates the same cylinders with the same format. ...
63 views

### Why doesn't RandomChoice work here? [closed]

I was using RandomChoice to run a simulation to test the probability that picking 4 marbles out of a bag containing 3 red and 7 blue marbles you get 2 red and 2 ...
143 views

### Extending a list

I have a range of n integers (always starting at 1) which are 1 apart, f.e. Range[10], Range[17] or ...
444 views

### Creating a fast random array generator

I want to create N x N array of random numbers. (N is an integer). The constraints are, each element should be between 0 to l(integer) ( here 0<= l <= N) and the sum of elements in each row ...
116 views

### RandomPoint in geographic region from Polygon[region_]?

How do you generate a RandomPoint in a geographic region? ...
112 views

### how to find circles that intersect a square

I use the following (based on ideas and functions I got as ansers in [1], [2] by, repsectively, @ybeltukov and @J.M.) in order to find random circles with centers inside a unit square that intersect ...
463 views

### Boundary condition for stochastic differential equation

I have a simple stochastic differential equation (SDE) with white noise: ...
99 views

### Hermitian Matrix

From Derbyshire's Prime Obsession, I would like to get the Mathematica code to generate a Hermitian matrix for evaluation and display. $256 \times 256$ would be nice. Random Normal distribution, ...
61 views

### StringReverse question

I was thinking about how to make this with the StringReverse, but I failed: I have a sequence of (for example) "FDSRTYNHFNKHLIUHG", I wish to reverse, but randomly long sequence reversed from a ...
418 views

### Random character change in a random place

I would like to ask for help in a Random Replace of character. For example: ORANGE and change 1 character randomly (random place and random character from ORANGE) in it into any character of ORANGE, ...
73 views

### Random Variable in Recurrence Function

Following the previously published question, I'm looking for the solution of RecurrenceTable with explicit random variable. For example, something like ...
231 views

### What will happen, if I don't specify random seed by SeedRandom function?

Suppose I want to run several times of the same code containing RandomReal function, but I don't initialise the random seed. What will happen? I tried, but each ...
357 views