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

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3
votes
1answer
405 views

Randomly selecting elements without repetition

I assigned energy values to each element in the array as per the program of Verbeia. The program looks like this ...
2
votes
5answers
630 views

Assigning a particular value to array elements

I have an array of 10000 elements. I want to randomly assign energy to these 10000 elements using Gaussian or Exponential distribution, such that each time a particular element is selected its energy ...
6
votes
3answers
1k views

Generating unique random number lists

I am new in programming. I have an array containing, let's say 20 elements and first I want to randomly select two elements from it and record them. Then I will select two elements from the array of ...
3
votes
2answers
122 views

Why do I keep getting 0.06 with WorkingPrecision->1?

I'm trying to generate a list of 1000 random numbers with WorkingPrecision->1. Is there any particular reason that I'm getting some entries as 0.06? I have tested the following lines: ...
2
votes
3answers
546 views

Some questions about random numbers

How can I get non-repeating random numbers from Mathematica 8? How can I know which distribution the numbers I get are? Can I choose the distribution I want together with the non-repeating random ...
7
votes
1answer
840 views

Wald–Wolfowitz Runs Test

Does Mathematica 8 implement Wald–Wolfowitz runs test for randomness? I can't find it in the documentation. I would like to test some fit residuals.
18
votes
4answers
2k views

Efficiently generating n-D Gaussian random fields

I am interested in an efficient code to generate an $n$-D Gaussian random field (sometimes called processes in other fields of research), which has applications in cosmology. I wrote the following ...
14
votes
5answers
824 views

Picking random items out of a list only once

I'm trying to create a function that randomly returns a value from a list but remembers the values that have been given before. At the end when the list is empty it should return an empty list. ...
16
votes
4answers
1k views

Random data generator

Inspired by Quality of random numbers I would like to set up a true random data generator in Mathematica. My idea is to use the static from an open microphone. I recall reading about extracting the ...
35
votes
3answers
2k views

Quality of random numbers

Mathematica has several ways of generating random numbers: Congruential, ExtendedCA, Legacy, MersenneTwister, MKL, ParallelGenerator, ParallelMersenneTwister, Rule30CA. For ...
7
votes
1answer
284 views

RandomVariate with a Discrete Distribution

Nature has provided me with a random variable $Z$ taking on the values $0, 1, 2, \ldots$, with probabilities $z_0, z_1, \cdots$. I can sample from the distribution of $Z$ reasonably efficiently (I ...
8
votes
2answers
497 views

Most efficient way to obtain samples from high-dimensional multivariate distributions?

Is MultinormalDistribution[] efficient and easy to use for high dimensions? I have a variable $n$ representing the dimension of a Monte Carlo integration I do on a ...
-11
votes
4answers
425 views

Going Beyond Pseudorandom Numbers

I cooked up this simple bit of code in hopes to exceed pseudorandom number generation maybe touch the face of true randomization: ...
25
votes
1answer
2k views

RandomVariate from 2-dimensional probability distribution

A probability distribution can be created in Mathematica (I am using 8.0.1) with e.g. ...
29
votes
6answers
2k views

Efficient way to generate random points with a predefined lower bound on their pairwise Euclidean distance

Using Mathematica what is an efficient way to generate a list of $n$ random two dimensional points $\{x_i,y_i\}$ where $i=1,...,n$ so that no two points $p_1$ and $p_2$ in the list has an Euclidean ...
11
votes
1answer
293 views

Are there rules of thumb for knowing when RandomVariate is more efficient than RandomReal?

Please consider the following: From a fresh Mathematica kernel, RandomVariate is more efficient for NormalDistribution but ...
4
votes
1answer
292 views

How to fix errors in Gram-Schmidt process when using random vectors?

I first make a function to get a random vector on unit sphere in a swath around the equator. That is what the parameter $\gamma$ controls; if $\gamma = 1/2$, the vectors can be chosen anywhere on the ...
3
votes
2answers
832 views

creating vectors with normal distribution of lengths

First consider vectors of unit length, say on the unit sphere. Now I want to give some magnitude to these vectors and I want the magnitude to be chosen from the normal distribution. In one dimension ...
10
votes
2answers
540 views

Creating randomly oriented planes

I would like to create randomly oriented planes. This is how I'm attempting to do that: I create a 2 random unit vectors, $\mathbf{v}_1$, and $\mathbf{v}_2$, in the $x$-$y$ plane I assume that if I ...
3
votes
1answer
168 views

Generate a new output using Manipulate

Thanks to methods found in the below, I was able to assemble those elements : Tile image on specific location without space between them How to combine images with the same dimensions in a grid? ...
21
votes
3answers
588 views

Which Distributions can be Compiled using RandomVariate

Recently, Oleksandr kindly showed a list of Mathematica commands that can be compiled. RandomVariate was part of that list. However, whether this can be compiled depends upon the distribution that is ...