# What is Random number: Definition and 69 Discussions

In mathematics and statistics, a random number is either Pseudo-random or a number generated for, or part of, a set exhibiting statistical randomness.
In common understanding, it's that all have an equal chance; conversely, none have an advantage.

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1. ### A 2D space and 1D time evolution of a random field

I want to develop a 2D random field and its change with time with constant velocity. My process: 1. Define a 2D grid [x, y] with n \times n points 2. Define 1D time axis [t] with n_t elements 3. Find the lagrangian distance between the points in space with the velocity in x and y ...
2. ### I Stratified sampling based on properties of random number streams

I recall seeing briefing notes dating from about the 1970's that advocated doing stratified sampling of the outputs of simulations by using strata based on properties of the random number streams. However, I don't recall how the strata were to be defined. Is this type of stratified sampling a...
3. ### Random Seed Choice for LAMMPS Molecular Dynamics Simulations

I want to create multiple molecular dynamics simulations using LAMMPS which are different only in the initial velocity of the atoms. LAMMPS allows you to use a random seed to generate an initial velocity. I plan to just use successive numbers, so if there are 5 simulations, the seeds would be...
4. ### Comp Sci C++ random number generation

The program works as intended. #include <iostream> #include <ctime> #include <cstdlib> int coinToss ();int main () { int tosses, result; std::cout << "How many coin tosses? "; std::cin >> tosses; size_t seeder = time(0); srand(seeder); for (int i = 0; i < tosses...
5. ### Identifying and understanding random number algorithms

Studying different ways to generate random numbers according to a distribution and the below algorithm describes the "box method". A search on Google led to the Box-Mueller method. Are they related? Also, what would be a simple implementation of this algorithm for ##f(x)=\sin{(x)}## on...
6. ### I Can a truly random number be constructed?

Here's a challenge of sorts, inspired by some previous discussions. You must choose a random number uniformly on the interval ##[0, 1]##. If the number is rational, someone wins a £1 million prize. If the number is irrational, no prize is won. It is your task to devise the method by which...
7. ### Entropy for Random Number Generation

I want to generate very random numbers. There's a few approaches to this, such as the audio input from a de-tuned radio, hooking user input such as mouse movement and hashing the results over a period of time etc.. My idea was to get a cheap Geiger Counter and just leave it monitoring background...
8. ### MHB Random Number Generation Avoiding Human Error in the Keyboard

Hi All Im hoping I am in the right area to ask this?!? Im looking for someones help. Is there a standard methodology or known equation for generating a random alpha numeric serial or incremental, which does not allow two characters to be used in sequence to each other which are near each other...
9. ### What lies left of a random number on a line of integers

When I pick a random number on a number line made out of integers, starting from zero and expanding infinite to the right, what can I say about the position of this random number ? To the right the amount of numbers is infinite. To the left is an amount, a number, so that is finite, but it has...
10. ### Math Game: Improve Ratio 9.66/10 by Guessing Better

I have a small mathematical game. A random number with uniform distribution between 1 and 10 is drawn, the player must guess any number except the the one drawn.The method I have found is by selecting the same number for every draw, the player will win 9 times out of 10. My question is , is...
11. ### MHB Estimating result of an iterative operation involving random number

Hi, Suppose there's an operation like the following: x(t) = x(t-1) + rand(m..n) with x(t) = current value x(t-1) = previous value rand(m..n) = equally distributed random real number in the range of m and n is there a way to estimate the value of x(t) after Y iteration without actually doing...
12. ### A philosophical question regarding random numbers....

A number can be random even if limitations are applied to the outcome - e.g. selecting a random integer between 1 and 5 restricts the outcome to one of 5 numbers, but the outcome is still random. The same would be true of between 1 and 2; although there are heavy restrictions, an unbiased...
13. ### Fitting a (Very) Large Random Number To A Formula

It has been a very long time since I have done any calc or hard math, I hope this question is in the right place. I have a HUGE number, that is random and big. What do I need to study/look at to create a formula that will generate just it?
14. ### Fortran [Fortran] How to loss different random number

Hello I am wondering how can I make sure that every number which I am losing will be different? I am using the following code: program lottery implicit none real(kind=4) :: x real(kind=8) :: y integer :: i, seed= 64256 call srand(seed) do i=1,6 x=rand() ! to make the lossing interval...
15. ### How does the Random number generator works?

Unfortunately I did not find suitable section to post this topic, if there is suitable one you may move it there. It is shown in the science documentary film “Through the Wormhole” (Season 2, episode 5 called "Is There a Sixth Sense?") how the consciousness acts on the Random number...
16. ### PDF of arccos and arcsin of a uniform random number

Homework Statement I want to find the PDF for arccos and arcsin of a uniform random number. Given: Y\sim\mathcal{U}(0,2\pi) \\ X = cos(Y) The Attempt at a Solution I started with trying to find the CDF: \begin{align} F_X& = P(X \le x) \\ & = P(cos(Y) \le x) \\ & = P(Y \le arccos(x))...
17. ### Code: Return random number less than specifed value

Code: Random number less than specifed value This isn't really a homework problem. I'm just doing this for fun and giggles. But given the nature of the forum rules, I'll post it here. Homework Statement Create a method (function) that returns a random number less than the specified...
18. ### Getting a random number with a distribution function

I have a mean mu, and an exponential distribution function. How do I use a random number, generated with a PRNG, to get a random number from the distribution? I know this is a really basic question. Please help :) Thanks
19. ### How Does a Random Number Generator Work and What is its Usage?

How does a random number generator work ? What is the usage of it ?
20. ### Fortran How can i create a random number distribution (FORTRAN)

Hello, I am working on the two point correlation function in dark matter haloes. Right now i need to create an array of rundom numbers to compute the estimators. My question is: How can i create a random distribution of points in the unit sphere (having in mind its curvature). I...
21. ### Random number generator circuit

How to build a random number generator circuit? Any good links / tutorials ? Thanks Ybqts
22. ### Dedicated random number generators

I was looking out for dedicated true random number generators and was surprised that there seem to be only very few around on the market. Anyone has experience here?
23. ### A proof that a computer cannot generate a truly random number?

I'm thinking about how to do a proof that a computer cannot generate a truly random number. Attempt. Let Ω = {ω1, ω2, ..., ωn}, a subset of ℝ, be all the numbers represented on a certain machine. A random number generator rand(), because its output is dependent on how many times it has been...
24. ### Bootstrapping using a random number generator?

I've been using this MATLAB function a guy gave me to crunch numbers on some EEG data from patients. If you have any idea what it does, let me know. From what I can tell it's somehow using random numbers to calculate the probability of getting certain power values? He doesn't comment his code...
25. ### Simulating a probability, use a random number?

Hello, I looking for some advice for a simulation. I know that when an electric car arrives at a destination there is a 70% chance that a charging point will be available. I'm building a model that models electric car journeys. When a car arrives at a destination would I simulate a random...
26. ### Convergence of non increasing sequence of random number

I have a non-increasing sequence of random variables \{Y_n\} which is bounded below by a constant c, \forall \omega \in \Omega. i.e \forall \omega \in \Omega, Y_n \geq c, \forall n. Is it true that the sequence will converge to c almost surely? Thanks
27. ### How to generate a random number according to this distribution?

f(x) = 1/(1+x^{3/2}) x>0 how to generate such a random number?
28. ### Random number from a unknown distribution

Dear all, I apologize if it is the wrong place, I don't know where I had to post this question since I'm not a mathematician. Well, suppose you have a set of numbers which can be describe by a unknown distribution. I just like to know whether we can use those numbers to generate a set...
29. ### Finiteness of a converging random number series

1. Imagine a positive point x not equal to zero. 2. Consider a randomly chosen point y with distance to zero less than x. 3. Let y=x. Repeat #2. 4. Is the sum of the y-values finite as y approaches zero?
30. ### Quantum and classical noise for random number generation

The gold standard for generating random numbers is the quantum effect of nuclear decay -- particles and photons being emitted from the atomic nucleus -- and unless you are one of those Hidden Variables types this is really random. The silver standard is thermal noise. There is a nice article in...
31. ### Generating a Random Number from an array for a blackjack simulator-Matlab

Generating a Random Number from an array for a blackjack simulator--Matlab I have a homework problem where I have to generate a single hand of blackjack to a player and allow the player to hit or hold. I'm ahving trouble generating the random card. My attempt: x =...
32. ### Given a random number from 0-3, return a random number from 0-6

This is actually for a program, but the challenging part is really the math. So you're given a number 0, 1, 2, or 3 and the probability of getting each is the same. Now given this random number, I need to output a number 0, 1, 2, 3, 4, 5, or 6 but the probability of getting each number needs to...
33. ### Can I Get a Flat Distribution with a Random Number Generator?

hello , i wanted to get a random number generator for colored as well as white noise. all numbers in the range should be equally likely to be produced.. ie, say within 1-100, 50 shouldn't hav an extra high probability. on the net i found this fortran program. http://fortran.com/gauss_random...
34. ### Probability of a random number - seems impossible

Hi guys, I have a question re: random numbers and probability. If I have a random number generator that generates a number between 1 and 10, and say I generate a kazillion of these numbers, then doesn't each number have the same probability of showing up? So then, after a kazillion numbers, I...
35. ### Random Number Generation - What is the 'middle one of three'?

Homework Statement The logistic random variable X has CDF: F(X) = exp(a + bx)/(a + exp(a + bx)), b>0 (i) Obtain a formula for random values of X in terms of R ~ U(0,1) (ii) Using the cdf, suppose that a certain application requires you to generate 'the middle one of three' i.i.d...
36. ### Random Number Generation Question

Homework Statement Consider the following probability table: X 1 2 3 4 P(X) 0.4 0.25 0.25 0.1 Use the rejection method to generate a random number. Use the following list of random numbers: 0.6072, 0.4893, 0.0899, 0.3456, 0.4419...
37. ### Correlated multivariable gaussian random number generation

\mathrm{prob} \propto \mathrm{e}^{-\frac{(a -x_1)^2}{2 \sigma^2}} \mathrm{e}^{-\frac{(x_1 -x_2)^2}{2 \sigma^2}} \mathrm{e}^{-\frac{(x_2 -x_3)^2}{2 \sigma^2}} \mathrm{e}^{-\frac{(x_3 -b)^2}{2 \sigma^2}} a and b are known real constants. Is there a way to generate x_1, x_2, x_3 independently...
38. ### How can I determine if a set of numbers is truly random based on a histogram?

[b]1. The problem statement If i generate a list of 300 random numbers in excel, each number between 1-50 for example, and i plot the frequency that each number comes in a histogram, how can i tell, looking at the histogram, if the numbers are really random? is there a certain distribution...
39. ### Quantum random number generator with radioactive decay

hello! i'm planning to build such a generator, but i have some questions: 1. what dimensions and materials are needed to shield one typical geiger-muller tube from the background radiation? 2. even with the complete protection, is it possible that the counter tube will trigger without...
40. ### MATLAB - random allocation of random number

Hi. I'm being asked to generate a random number either 0 or 1 and then to randomly allocate this 0 or 1 to one of 100 groups, and then to repeat this many (a million) times. So... I can easily generate randomly either a 0 or 1 by randint(1), but how do I randomly allocate this to 1 of 100...
41. ### How to get Excel to generate any random number besides x?

Here's my dillemma: I'm writing up a spreadsheet where we have 100 passengers on a plane. Excel randomly generates their assigned seat, and the seat they end up taking. But the problem is, I need to make it so that Excel does not generate the same number twice.
42. ### Fortran How can I generate a random number between 1-10 in Fortran 90?

I'm trying to contruct a program that will generate a different random number between 1-10. I am not sure how to make it only 1-10. PROGRAM guess USE const IMPLICIT NONE INTEGER::i REAL(kind=dp)::x call random_number(x) WRITE(*,*) 'x=',x END DO END PROGRAM...
43. ### Can a super being create a pure random number generator?

The only requirement is that the pure random numbers generated have to be purely random to its creator, not for some other inferior species. (To keep Evo happy, a super being is someone who is omniscient and omnipotent.)
44. ### Random number with which distribution

Hello, I am trying to find a clean solution for this (i.e. straightforward and academically acceptable). I appreciate if someone can help me. 1- I need to select between selections 1 to n (in my case 1-8 ). However each preceding item should have higher probability than the next one. For...
45. ### Distribution of the decimals of a random number

Homework Statement Let U = 0.X1X2X3... be a random number in (0,1]. 1) Find the distribution of every decimal digit Xi, i = 0,1,2... 2) Show that they are independent of each other The Attempt at a Solution I could use a hint for N°2. I have an idea, but I think it's wrong...
46. ### Java Java random number generator help.

Hi, I'm trying to get it so that when the program initiates, if the random number is greater than 3, I turn left. here is what I have in summary; int rt=3; Random ra = new Random(); for (int c = 6; c <12; ++c); { } if(rt<ra) {...
47. ### MATLAB I in partioning bits of random number in matlab

I need help in partioning bits of random number in matlab! Hey guys, I really need your help here...What i wanted to do actually is to partition the bits into 4 smaller group.. If anyone of you can give me a basic coding of it or maybe u can check if there anything wrong wit my coding...
48. ### Creating Equal Probability Random Values with a Hardware Random Number Generator

I've been experimenting with a hardware random number generator. My circuit amplifies transistor noise and converts it to a digital output. My program (.Net) reads the output into an array of double precision values. My voltages range from -7 to 7 (well within the range of my ADC) and have 16...
49. ### Expectation and variance of a random number of random variables

Homework Statement Let X1...XN be independent and identically distributed random variables, N is a non-negative integer valued random variable. Let Z = X1 + ... + XN (assume when N=0 Z=0). 1. Find E(Z) 2. Show var(Z) = var(N)E(X1)2 + E(N)var(X1) Homework Equations E(Z) = EX (E(X|Z))...
50. ### Single or multiple random number generators?

I'm programming in Java and using the Random class and I'm not sure if it makes a difference whether I use a single accessible Random object for the whole program or if I should create multiple instances (one for each object needing it?). Are there disadvantages to using one instead of the...