# Tagged Questions

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

214 views

### How to generate a random signal consisting of the specified functions

Let's assume that I have some particular signal on the finite time interval which is described by function $f(t)$. It could be, for instance, a rectangular pulse with amplitude $a$ and period T; gaus ...
167 views

### Matrix and random, weighted assignment of rows

I asked a question in this category previously but my problem has changed. On one hand, I have a large number of data files as .dat format, and on the other hand, I have a matrix ...
223 views

### Generating $n$ random samples every time

Is it possible to generate $n$ random samples, and always ensure that $n$ samples are generated? eg For $n=5$: ...
419 views

### random split a dataset

I've got a very simple problem, but not so trivial. I need to split a dataset (input and output data) in three part randomly: training set 70%, validation set 20% and is test set 10%. First of all ...
57 views

### Replicability of RandomVariate within a function?

I have a rather basic question but can't figure out a foolproof answer. In the following code, I build a function which returns the mean difference between successive elements of a vector created from ...
34 views

### Table of values for functions with random variables [duplicate]

I'm trying to get a table of values for functions with random variables. First of all, i have a function like that: ...
864 views

### Distribution of 10 points within a unit square

Related to some packing problems, following problem arose: Distribute 10 points within a square of sides 1, so that minimal distance between them is maximized. With the help of random simulation, or ...
267 views

### Importing a text file into a matrix format

I am attempting to perform a comparison of pseudorandom number generation with the RAND Corporation's "A Million Random Digits with 100,000 Normal Deviates" for a Computational Physics course. I have ...
207 views

### How do I select only those lists whose elements are all above a certain number?

I'm essentially doing coin flips, using RandomReal to populate a bunch of lists, each with 8 elements. I then want to select only those lists for which all elements are greater than a certain number, ...
327 views

### Expectation of a family of random variables

I did some search here, but seems that no one asked about this. I want to define a family of independent and identically distributed random variables, $x_1,...,x_n$, and then calculates the expected ...
72 views

### RandomVariate does not evaluate a Hyperbolic Distribution

Any Idea why I can't get a result from this expression: ...
221 views

### How to efficiently distinguish the rewired edges in WattsStrogatzGraphDistribution?

The WattsStrogatzGraphDistribution function is a way to construct random graphs based on Watts and Strogatz small world model. The ...
660 views

### Randomly selecting and reinserting a subset of elements in a list

This question is similar to my other question: How do I randomly select 'k' positions in a list and shuffle their respective elements without effecting the other elements? Imagine first a ...
224 views

### How do I randomly select 'k' positions in a list and shuffle their respective elements without effecting the other elements?

Imagine I have some list: listA = {"a","b","c","d","e","f","g","h","i","j"}; I'd like to randomly select k positions in the ...
337 views

### Generating a random sample of elements from a list that includes a subset of the list

Imagine I have a list: tList = {item1,item2,item3,item4,item5,item6,...}, and I'd like to take a random sample of numItems ...
92 views

### How do I keep a random value associated with a locator point as points are added?

I have a Manipulate to which I am adding and removing Locator points (one of which is different from the others, though that is ...
223 views

### Put random points into a specific 2D subregion

I want to cover a particular subregion of the x-y plane with a random distribution. As this particular region is not a circle I encounter some problems declaring the permitted zone where to put ...
1k views

### Fast code to generate large random graph with fixed degree sequence

I'm trying to create a function so to generate large random graph with a fixed degree sequence $\{v_1,v_2,\dots,v_N\}$, where $N$ is the number of vertices in the graph. The Mathematica function that ...
296 views

### Index of iteration inside NestList [duplicate]

I have a list of RandomReal: delta = RandomReal[{-0.01, 0.01}, 1000] I want to add each element of the list to the ...
204 views

### How to update a list in a function in each iteration

There is a list with numbers 1 to 8 ( p1 ) and another list (j) which contains 4 numbers which shows different 4 positions of ...
581 views

### Monte Carlo integration with random numbers generated from a Gaussian distribution

I want to do numerical integration of some functions using the Monte Carlo method. The default setting for the Monte Carlo method is to use a uniform distribution as far as I know. How can I change ...
229 views

### How to replace identical positions in two different lists

Assume that I have two lists like : list1={1,2,3,4,5}; list2={a,b,c,d,e}; I want to replace some elements from list1 into <...
74 views

### How to put some values from a list into a function in a Do loop

I want to program a code in MATHEMATICA in order to calculate some values in different iteration. For example, assume this list: list={1,2,3,4,5} Now assume that ...
201 views

### Avoid making repeated Random Integer in different iterations

Assume following code : Do[ i1 = RandomInteger[{1, 5}]; i2 = RandomInteger[{1, 5}]; While[i1 == i2, i2 = RandomInteger[{1, 5}]] , {k, 1, 4}];` This ...
400 views

### Making Monte Carlo simulation with ParallelTable

I would like to to MonteCarlo simulations of various regressions - basically, doing OLS under various conditions to test approaches. On my macpro 2x 2.8 GHz quad core Xeon, 32 Gb RAM DDR2 @ 667 Mhz, ...
90 views

### Multiplying a list and randomly re-assigning that list to a series of numbers

I'm trying to write a script that matches a particular element to a coordinate. Let's say there are 24 coordinates; and that fractionally a:b:c:d:e is 18%:18%:18%:18%:27%. Instead of matching 4 of a, ...
371 views

### Inconsistent DistributionFitTest results?

In pondering this question, I used Mariana's function to generate the following data. ...
3k views

### What is the best distribution for my histogram?

I defined a security bound for a random walk (cube with 15 length) and I have this code to obtain a sample of the random times at which the random walk crosses the boundary for the first time: ...
295 views

### Sample of the random times at which the random walk crosses the boundary

I defined a security boundary for a random walk: ...
235 views

### Color of first and last point in a graphic

I'm trying to make a graphic of a random walk in 1D, but i want that the first and the last point have a color (in this case the first one red and the last blue), but i dont know what i'm doing wrong.....
1k views

### Random walk on a sphere

I'm trying to program a random walk on a sphere with Mathematica. I found this code while I was searching, but I'm not getting results from it. I waited an entire day, but my PC didn't finish ...
222 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 ...
103 views

### Converting problem into form involving Probability

I want to solve the following problem symbolically, using Probability: What is the probability of the first random variate of a set to be present more than once,...
186 views

### Performance on Multinomial Deviate is slow

Most of the time in my program is spent on this single line of code: out = RandomVariate[MultinomialDistribution[nt, tmp]]; ...
116 views

### RandomSample Bug?

I was using RandomSample with very skewed weights. I am asking for a random sample of 6 numbers 1 through 100 without replacement. In the screen shown, the weights for 1 through 6 are 100 000, with ...
141 views

### Algorithm in RandomChoice[{w1,w2,…}->{e1,e2,…},n]?

I wonder if someone happens to know the actual algorithm implemented in the particular overload of RandomChoice that handles explicitly presented discrete ...
161 views

### BlockRandom and NestList: how get random maps with the same noise?

I need to compare solutions in random systems with the same noise and different initial conditions. Here I run twice a random map with the same initial condition, inside a ...
560 views

### How can I generate and randomly assign color to annular sectors?

How can I generate such an image and fill every annular sector with a random colour?