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# Questions tagged [random]

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

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361 views

### Randomly distribute numbers to lists

I have 4 empty lists. I would like to randomly distribute numbers from 1 to 10 to these 4 empty lists. How can I add integers to lists randomly? For example: ...
321 views

### Sum of Random Integers

I am trying to get a list of numbers with at least 1000 sums as possible, using random numbers from 1 to 10. But I don't want to get blank list output. How can I only get a list of numbers greater ...
39 views

### How to create 2 lists of RandomIntegers based on condition?

How do i create 2 lists of RandomIntegers that are the same at certain points based on a condition. For example there are three lists: List A List B List C List C already exists. I am trying to ...
90 views

### How to match random number generator to R?

Although I know the algorithm that R is using for pseudo-random numbers I am unable to match the generation of random numbers. ...
197 views

### Generate a smooth random function (2D curve) with endpoints specification?

Here is a PDE example, adapted from Wolfram Documentation: ...
64 views

### Drawing random numbers from TransformedDistribution

Suppose I have created the following TransformedDistribution: ...
65 views

### How do decrease uncertainty of Monte-Carlo integration?

I have some function of many arguments and need to integrate it over the region given by the products of Heaviside theta functions. Namely, I write, say, ...
98 views

### How to select random number of elements from a list?

Assume that I have a list a = {1,2,3,4,5,6}; and I want to have a function that outputs a subset of the list such that with probability p=0.2 each element will ...
58 views

### Random points from an image using a BernoulliDistribution

I am a Mathematica newbie. I need to sample random points from an image which I have stored in a variable img as: ...
162 views

### Why does Monte Carlo integration underestimate my integral as integration range increases?

I'm having a huge problem with Monte Carlo integration. This simple example adequately shows the problem. ...
49 views

### Matrix Randomization

Is there a way to take a 20x20 array and replace 2 random parts of this array with a 2x2 matrix? I've tried rvalues = ConstantArray[r, {20, 20}]; to make the ...
68 views

### Negative values with RandomVariate

I am using the following code to generate some random number from a custom distribution: ...
46 views

### Am I using RandomVaraite and ProbabilityDistribution correctly?

The following code does not produce an output on my Mma (version 11.3 for Windows) ...
153 views

### How can I get new random values with each blank in ReplaceAll?

Is there any way to get different values for different blanks with ReplaceAll[]? For example, I would like to do something like: ...
2k views

### Efficient way to simulate thousands of Markov chains

I am currently trying to simulate relaxation of a protein population while maintaining the stochastic properties of the system. For this, I used a Markov chain to describe the temporal evolution of ...
229 views

### How can I delete a random part of an expression?

I have the expression: Times[0.19157500241430547,Power[Plus[0.7235014213631388,k,Times[-1,Power[m,c]]],Times[g,z]]] Also represented as: ...
167 views

### Improving the run time of random walk simulation

One of our professors told us that during his thesis he used Mathematica in simulating it since it is about networks, I don't know how he did it but all I know is he said it took about two weeks to ...
256 views

### Construct Distribution Histogram From Random Variable

Given a Beta Random Variable $X$ with parameters $\alpha, \beta$ and a positive constant $n$, suppose I am interested in the distribution of: $$Y:=\lfloor nX\rfloor$$ Suppose I want a histogram ...
76 views

### Apply RandomReal to list in list in Mathematica

I have a big list: {{1,1,1},{1,1},{1,1,1,1,1,1,1}....{1,1,1,1}} How can I apply RandomReal to every single element in the list?
573 views

### Evenly spaced points on boundary of polygon

I have a polygon and I would like to generate $n$ evenly spaced points along the boundary.
142 views

### Acceptance Rejection Method

I need to generate a random number (real) and then test if this number works on my pdf. if it works i append it to a list. if it doesn't, i reject it. Until now i have done this: ...
113 views

### Generating random coordinates (3D) with constraint

I have been trying to generate random $(x,y,z)$ coordinates (i.e. for 15 ellipsoids) so that they obey following constraints: ellipsoid's length is constant, ellipsoids do not intersect (fulfilled ...
112 views

### Optimize RandomVariate for a $1/x^4$ distribution

I'm working with the following code, where I define a probability distribution proportional to $1/x^4$. ...
86 views

### Generate random point on the external surface of this complex geometry

This is a followup to this question of mine. How do I generate a random point on the most external surface of this complex geometry? ...
36 views

### How to ask FindClusters to return the loss function value in the output?

I have some data points pts as below:- pts = BlockRandom[SeedRandom; RandomReal[1, {100, 2}]]; Now I want to separate ...
781 views

### Generate “nice” random matrix

I don't frequent this community so please give criticism if this is a poor question. I am trying to make a tool which generates a small (say, $4\times 4$) matrix with integer entries which has a "...
95 views

### Bizarre error messages when monitoring random integers

I am doing tbl = {}; Monitor[ Do[AppendTo[tbl, RandomInteger[{1, 100000}, 2]], 100000], Length[tbl] ] (well in fact I am doing something less boring but what I ...
88 views

### How to generate a random real under a specified density function?

I want to generate a random real in the interval [0,1] according to the density function f(x) = 2x.
403 views

### Random walk in one dimension — meeting of two particles

I'm new to Mathematica and still teaching all by myself, hope you bear with me. I have the code: ...
85 views

### RandomVariate with a custom distribution [duplicate]

I have a customized distribution and I have to draw some random number from it. How do I use RandomVariate to draw random number from a custum distribution? My naive attempt ...
252 views

### Generate a random pattern with at-most n repeated consecutive elements

I want to generate a random pattern which has at-most n (>= 0) repeated consecutive elements from a sample space. The following example explains what I mean: ...
75 views

### Getting PDF from imported Histogram

So I'd like to create a probability density function from an existing histogram from a program that I use. My input data is of the form ...
146 views

### Sampling “Random” Cyclic / Acyclic Graphs

This is an extension of RandomGraph with specific constraints Where @Histograms wanted to make $n$ random graphs with a specific constraint (in @Histogram's case, having 2 vertices each with exactly ...
134 views

### Uniformly distributed numbers fulfilling conditions

I would like to generate 10 random lists of four elements (t, l, p, ...
647 views

### Smarter Shuffle of a List

I have a 2D matrix representing a keyboard: ...
2k views

### Can this code be changed to run faster?

I've worked for several days trying to get this code to run faster. The imported data is 15MB. ...
59 views

### Evaluation Time of RandomVariate Function

This question is about the runtime of the function RandomVariate. Take a simple normalized Gaussian distribution G on the real line, I tried to generate N random ...
178 views

### Creating a random matrix of no duplicates in both row and column from a given set list of elements

Say I have a list of letters {A,B,C,D,E,F,G,H}, I want to create an $4\times 8$ array where each row must not contain duplicates and each column must also not contain duplicates. Naively writing: <...
136 views

### Is a probabilistic primality test implemented in Mathematica?

Imagine that I need to verify that a specific integer, like $n = 10^{1347}+3049$ is prime. ProvablePrimeQ takes a lot of time, and, even if it will eventually work ...
458 views

### Creating a less random list

I'm trying to create an list like {1,3,2,5,8,7,9}, or {2,1,5,6,4,7,9}, that the elements in each list is sorted in a rough order,...
136 views

### Random particle motion

I have a foundational function that allows me to simulate particles moving in a box according to some movement function. The code is here: ...
52 views

### Looking for a way to run through every time step of a cellular automaton function with random seeds

I have been creating 2D cellular automaton functions in Mathematica and I would like the output to be a graphical representation of the array at each time step. I know I can do this with ListAnimate: ...
188 views

### Getting random points on a mesh region

So I have a region defined by a MeshRegion,like ...
71 views

### Random normalised variable generation

I want to generate 8 random variables (in reality to form 4 complex numbers) such that the sum of the 8 variables squared is equal to unity. The aim of generating such numbers is to perform a quantum ...
137 views

### How do I use the values generated in a for-loop in my first iteration to my next iteration?

This one is somewhat hard to explain, but I'll try my best to. I'm trying to generate a list of numbers (containing only pi/10, 0, -pi/10). Numbers are randomly selected from these 3, where the ...
87 views

### Defining a random potential on the unit square

I'm trying to define a random potential on the 2D unit square. For some fixed j, I want to decompose the unit square into $2^{2j}$ smaller squares with sides length $2^{-j}$. On each of the smaller ...
37 views

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95 views

### RandomPoint not evaluating on RegionQ and ConstantRegionQ regions

When attempting to recreate and generalise the MatLab code for Random Vectors with Fixed Sum by first principles I came across a few issue with RandomPoint. ...