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

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6
votes
2answers
278 views

Generated Numbers under a constraint?

Let's say I have five four dimensional vectors $p_i^\mu=(p_i^1,p_i^2,p_i^3,p_i^4)$ with $i=1,2,3,4,5$. Now, I want to fill the entries of these vectors ($4\cdot5=20$ in total) with some numbers, but ...
1
vote
4answers
459 views

How do I create a list of 25 random quadratic equations in the form ax^2+bx+c?

My teacher suggests using the RandomInteger command along with the Factor command, but I cannot figure out the syntax. A, b, and c need to be non zero integers between -10 and 10.
0
votes
0answers
47 views

Using an Interpolating Function as a probability density function [duplicate]

I have seen a couple of similar questions but have not been able to figure out a solution for my particular problem. I have a probability density function of two variables ...
7
votes
3answers
574 views

How to randomly erode a 3D distribution of points with Mma 7.0?

Suppose we have a 3D distribution of points, like the spherical ball example below : ...
-4
votes
1answer
606 views

How to generate this fractal-like 3D distribution of points in Mma 7.0?

I would like to produce some 3D distributions of points using Mathematica 7.0, that look like the picture below : How could I do that ? What are your suggestions ? What Mma 7 codes could do a ...
4
votes
3answers
334 views

Creating a function with integral zeroes of the 0th, 1st, and 2nd derivatives

I would like to be able to randomly generate functions, each of which satisfies $f : [-10, 10] \rightarrow [-10, 10]$ All the zeroes, critical points, and inflection points have an integral ...
2
votes
2answers
131 views

Random Choice: List Format & Minimizing Memory Use

This is a two part question, and for that I apologize.. but they're related! Here's what I'm working with: ...
0
votes
2answers
314 views

Generating a random tree of given cardinality, depth, and labeling

For demo, exploration and teaching purposes, I would like to be able (and asking you for help) to generate these special instances of trees: For given: N - number of nodes in the tree D - depth of ...
2
votes
2answers
81 views

Avoiding RandomVariate update with use of Locator

I am preparing an activity that simulates the response from a noisy spectrometer. The function I use to generate the data has the form: ...
1
vote
1answer
146 views

RandomVariate[LogNormalDistribution] works not as expected

I currently simulate data with a lognormal distributed covariate. I used the following code to check the generated random numbers (with Mathematica 9). ...
8
votes
3answers
305 views

When does a list contain only ones?

I am starting with a list of length n that contains all -1's. For instance, when n = 6 the list is {-1, -1, -1, -1, -1, -1}. I ...
2
votes
2answers
328 views

Fast randomization of a graph, while keeping the graph connected

I'm looking for a very efficient method for randomizing graph of a given size (N nodes, L links), but keeping them connected. Assume you have the adjacency matrix A of a given connected graph. You ...
2
votes
1answer
57 views

How to randomly select and open a notebook using CDFPlayer

I have a lesson notebook for a class I am teaching. I'd like to separate the lesson content and the practice problems. Students are using the CDFPlayer program, not Mathematica. I created a button ...
110
votes
7answers
19k views

How to generate a random snowflake

'Tis the season... And it's about time I posed my first question on Mathematica Stack Exchange. So, here's an holiday quest for you Graphics (and P-Chem?) gurus. What is your best code for generating ...
18
votes
4answers
2k views

Finding the volume of a sphere using the Monte Carlo algorithm

I used the following code to find the volume of the sphere $x^2+y^2+z^2 \leq 1$ in the first octant: ...
12
votes
4answers
600 views

Why is Poisson Random Deviate Generation so slow?

I am generating Poisson deviates for some numerical work. Mathematica 9.0.1 is very slow in generating these random numbers, as can be seen below. ...
2
votes
2answers
273 views

How to restore default seed generation in SeedRandom[] when specifying method?

I want to generate low-discrepancy sequences and for that purpose I use SeedRandom[], like: ...
-1
votes
1answer
117 views

map rational number [duplicate]

I am trying to map this function ((-1)^(1/Denominator[#]))^Numerator[#]==(-1)^#& to a fairly big list of random rational numbers I am trying to get this to ...
6
votes
1answer
188 views

Random filling of L-length line with l-length segments

I have discrete L-length line filled randomly with 2-length segments so its cover line with gaps 0 or 1. So we can describe cover configuration as sequence of gaps such as {0,0,1,0,1}. How I can ...
1
vote
1answer
148 views

Random number generation from a given distribution [duplicate]

Is there any way to obtain random numbers from a user defined continuous distribution in Mathematica? Thank you very much
1
vote
3answers
185 views

Number theory: Problem involving rational numbers

Use RandomRat to test whether ((-1)^(1/Denominator[q]))^Numerator[q] is identical with ...
14
votes
1answer
889 views

Uniformly distributed n-dimensional probability vectors over a simplex

What's the right way to generate a random probability vector $p={p_1,\ldots,p_n} \in {(0,1)}^n$ where $\sum_i p_i=1$, uniformly distributed over the $(n-1)$-dimensional simplex? What I have is ...
7
votes
1answer
210 views

RandomVariate does not fill range of PDF of distribution

I've declared my own probability distribution as follows dist[a_, b_] := ProbabilityDistribution[Cos[(b x)/2]^2 Sinc[a x]^2, {x, -400, 400}]; When I try to ...
10
votes
2answers
1k views

How could I generate words starting with P,h,D?

A friend of mine is a PhD candidate and posted a picture on Facebook with funny words starting with 'p', 'h' and 'd' like "Please hire. Desperate" or "Permanent head Damage". I thought I could try and ...
8
votes
3answers
619 views

Create sine function with random increase in phase

I am trying to simulate a signal that randomly increases its phase, so far I have tried two thing but neither worked. I usually use matlab but I want to learn some Mathematica so I thought I would try ...
21
votes
3answers
1k views

Generate a Random Polygon

Does some package exist with a function that takes a parameter $n$ and generates a random 2D $n$-sided simple polygon (convex or non-convex), possibly within a certain bounding box? It does not ...
32
votes
5answers
739 views

obtaining random element of a set given by multiple inequalities

I try to obtain random elements from a set given by multiple inequalities. This is of general interest to me, but let me present one example here: I have multiple inequalities specifying half spaces ...
15
votes
8answers
418 views

Is it possible to use RandomChoice to choose without other choices being evaluated?

I'm trying to do this: i1 = 1; i2 = 1; RandomChoice[{ (i1 = i1 + 1), (i1 = i1 - 1), (i2 = i1 + 1), (i2 = i2 - 1)}] In order to chose randomly which ...
1
vote
2answers
102 views

HoldForm and RandomChoice

I'm trying to get random expressions displaying. For that, I'm starting with addition, multiplication, substraction and division. When trying out this code ...
4
votes
1answer
693 views

How do I get a list of unique random integers? Avoiding numbers being drawn twice [duplicate]

I am trying to get a set of random integers for which I used the function RandomInteger[{1, 50}, 5]. That way, however, there is the chance to get doubles such as ...
3
votes
2answers
1k views

How to generate a random matrix with specific parameters?

I want to use Mathematica to generate a random matrix with given dimensions, entries coming from a finite set, and with a determinant also coming from a finite set. (It's very important that the ...
13
votes
1answer
415 views

Randomness test suites that can be invoked from Mathematica

There are several test suites referenced at csrc.nist.gov designed to test a (pseudo-)random byte sequence for randomness, and discover possible skews, correlations, patterns, or other hidden ...
-6
votes
1answer
453 views

random number visualization without generator (Spectral Test) [closed]

Does anyone have codes for using only numbers to make this kind of random-number visualization and not requiring a number generator? ...
0
votes
1answer
106 views

Random variation inside NMaximize

I am using NMaximize as following code. ...
1
vote
2answers
297 views

Problem in simulating discrete time stochastic

I have been playing with some stochastic questions and specially the problem here.It seems no matter for the first time in bet, gambler is going to lose the first bet.Am I right?How can we correct the ...
5
votes
2answers
473 views

Adding noise to nonlinear control system using NDSolve

I have a nonlinear control system ...
4
votes
2answers
463 views

Boundary condition for stochastic differential equation

I have a simple stochastic differential equation (SDE) with white noise: ...
8
votes
1answer
730 views

How can I randomize order of elements in a list?

Is there a straightforward way to go from an ordered list like: ord = {a, b, c, d, e, f, g, h} to a disordered list like: ...
9
votes
1answer
244 views

Have the Random functions changed?

I re-ran a program I wrote for Mathematica v8, now on v9, and it appears to generate different RandomInteger numbers, even though I use the same ...
0
votes
2answers
288 views

Random variates in Recurrence Function

I'm completely new to Mathematica and can't seem to find an answer elsewhere so hopefully I can get some help here. I'm trying to plot a recurrence relation, where a random variate is generated at ...
3
votes
2answers
230 views

Bounds on random number

I have a Markov Chain Monte Carlo code that uses a chi squared function to fit some data. I am running into an issue now with getting unrealistic values for some of the free parameters in the code. ...
4
votes
1answer
1k views

White noise $\eta(t)$

How to make a random function $\eta(t)$ to insert in a differential equation for NDSolve? Edit: example: to solve equations like $\frac{dx}{dt}=\eta(t)$
1
vote
1answer
221 views

Safe values of $\mu$ and $\sigma$ when randomly sampling from a Log-Normal Distribution?

I believe I'm obtaining overflow errors when randomly sampling from a log-normal distribution with the command: RandomVariate[LogNormalDistribution[μ, σ], 1] ...
2
votes
0answers
774 views

Calculate variance of random walk?

How can I symbolically calculate the variance of the following random walk in Mathematica? Given several discrete random variables such that $p(Z_i=1-2k)=p$, where $k$ is a small real number, and ...
17
votes
1answer
766 views

Mathematica giving infinity as a random number!

I am trying to generate several random numbers from normal distribution using Mathematica. The following is the relevant code: ...
2
votes
2answers
383 views

Help with 1-dimensional random walk [closed]

I would like to simulate the evolution of a bankroll of a 2 player game where you have the probability of winning p. If a player wins, the bankroll grows by 1 unit minus a fee that each player pays, ...
15
votes
3answers
628 views

How to Import random elements of huge data files

I am calculating huge data files with an external program. I would like then to import the data into Mathematica for analysis. The files are 2 columns and up to many millions of rows. So for ...
14
votes
1answer
732 views

Simulating discrete time stochastic dynamic systems

What is the canonical way of simulating discrete time stochastic dynamical systems in Mathematica using the new functionality of Random processes? To take a concrete example, lets consider the ...
2
votes
1answer
138 views

How to label vertices in a grid with random integers?

I would like to assign each vertex a random number with the minimum bound equal to the smallest vertex and the maximum equal to the value of the largest without repeats. For example, in a 20x20 grid, ...
2
votes
2answers
217 views

Illustrating half life

I'm teaching some lessons on negative exponents and one application listed was half life since the rate of decay can be written as 2^-1 every __ years. I found this nice animation on the net. ...