set the random seed in julia generator of random numbers

Question

I would like to do a couple of checkings using the random generator for normal distributed numbers in julia. So what I would like is to obtain the same sequence of pseudo-random numbers.

Actually, I do random matrices, so I would like that both of my programs generate:

A = randn(dim,dim)                                                                                                                                                                           
H = (A + A')/sqrt(2)

the same H-matrix

IainDunning · Accepted Answer · 2019-05-03T17:41:07.330

44

Updated answer, for Julia 0.7 onwards.

import Random
Random.seed!(1234)
dim = 5
A = randn(dim,dim)
H = (A + A')/sqrt(2)

Previous answer, for Julia 0.6 and earlier.

You are looking for the srand function, e.g.

srand(1234)
dim = 5
A = randn(dim,dim)
H = (A + A')/sqrt(2)

Will always produce the same results.

edited May 03 '19 at 17:41

answered Jul 29 '14 at 00:49

IainDunning

11,546
28
43

which is the range of the argument of srand? – user2820579 Aug 07 '14 at 22:52
There actually multiple versions of `srand`, try `methods(srand)` and `?srand` for more info. – IainDunning Aug 09 '14 at 08:27
The `srand` documentation link is dead. – a06e Jan 30 '17 at 17:53
@becko not anymore! :) – ahogen Oct 30 '17 at 21:42
2

srand does not exist in Julia 0.7/1.0 – crlb Oct 18 '18 at 07:12
hasn't ``srand`` been deprecated in Julia >1? Would you update your answer? Thanks. – PatrickT Jan 30 '19 at 14:22
Updated for modern Julia. – IainDunning May 03 '19 at 17:41

score 11 · Answer 2 · answered Sep 24 '18 at 19:29

11

In Julia 0.7/1.0, you can use Random.seed!(1234); https://docs.julialang.org/en/v1/stdlib/Random/index.html#Generators-(creation-and-seeding)-1

answered Sep 24 '18 at 19:29

Rob Donnelly

2,256
2
20
29

2

I think it is the only function you can use now. – crlb Oct 18 '18 at 07:13

score 1 · Answer 3 · answered Aug 29 '21 at 19:02

I think Random.seed!(int) applies only on the next random for some reason. you need to reuse it every time you call. You can set the random seed as a function though like

function rr()
    rng = MersenneTwister(22);
    return rng
end

and then call in inside the rand() function like

rand(rr(), 1)

Example

set the random seed in julia generator of random numbers

3 Answers3

Linked