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SeedRandom
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SeedRandom

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resets the pseudorandom generator, using s as a seed.

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resets the generator, using as a seed the time of day and certain attributes of the current Wolfram System session.

Details and Options

  • You can use SeedRandom[s] to make sure you get the same sequence of pseudorandom numbers on different occasions.
  • SeedRandom affects RandomInteger, RandomReal, RandomComplex, RandomPrime, RandomChoice, RandomSample, and RandomVariate.
  • Possible settings for the seed s include:
  • RandomGeneratorState[…]a RandomGeneratorState object
    nan integer
    "seed"a string
    Automaticautomatically choose whether to reseed based on options
  • SeedRandom returns a RandomGeneratorState that for deterministic generators can be used as a seed in order to reproduce random sequences.
  • SeedRandom[Method->"method"] specifies what method should be used for the pseudorandom generator. If "method" has been previously used, this form does not reseed it.
  • SeedRandom[n,Method->"method"] resets the generator, specifying both a seed and the method to use.
  • SeedRandom[n] affects only the current generator; SeedRandom[n,Method->All] affects all generators for which seeds have been given.
  • Typical possible methods include:
  • "Congruential"linear congruential generator (low-quality randomness)
    "ExtendedCA"extended cellular automaton generator (default)
    "OpenSSL"OpenSSL cryptographically secure generator
    "MersenneTwister"Mersenne twister shift register generator
    "MKL"Intel MKL generator (Intel-based systems)
    "Rule30CA"Wolfram Rule 30 generator
  • Different methods may give sequences with different levels of randomness.

Examples

open allclose all

Basic Examples  (1)Summary of the most common use cases

Use SeedRandom to make random numbers repeatable:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-xg2
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0i1irpdba-kqj
Out[2]=2

Scope  (3)Survey of the scope of standard use cases

The seed can be a string:

In[3]:=3
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https://wolfram.com/xid/0i1irpdba-gwu
Out[3]=3

Reseed the current random number generator:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-vle14k
Out[1]=1

Create a sequence of 5 random reals:

In[2]:=2
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https://wolfram.com/xid/0i1irpdba-6it8xp
Out[2]=2

Reseed using the RandomGeneratorState object returned by SeedRandom:

In[3]:=3
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https://wolfram.com/xid/0i1irpdba-n1ipya
Out[3]=3

The sequence of random real numbers is reproduced:

In[4]:=4
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https://wolfram.com/xid/0i1irpdba-gvl4ht
Out[4]=4

SeedRandom affects all random generators:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-yp5
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0i1irpdba-uyh
Out[2]=2

Options  (2)Common values & functionality for each option

Method  (2)

Switch to the Mersenne twister generator:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-dp2m4b
Out[1]=1

Random numbers are now generated using it:

In[2]:=2
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https://wolfram.com/xid/0i1irpdba-ieeqsj
Out[2]=2

A specific seed will affect the current Mersenne twister generator:

In[3]:=3
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https://wolfram.com/xid/0i1irpdba-bw1c3j
Out[3]=3

Give a seed to all initialized generators:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-b25860
Out[1]=1

Applications  (2)Sample problems that can be solved with this function

Reproduce a part of a computation that uses randomness:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-dlilav
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0i1irpdba-c6ezbe
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0i1irpdba-j1ygok
Out[3]=3

Write a function that uses randomness, but returns predictable results:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-hq4qp7
In[2]:=2
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https://wolfram.com/xid/0i1irpdba-rc9lnp
In[3]:=3
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https://wolfram.com/xid/0i1irpdba-denwar
Out[3]=3

Using the function again with more points just adds the additional points:

In[4]:=4
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https://wolfram.com/xid/0i1irpdba-j378f9
Out[4]=4

Properties & Relations  (4)Properties of the function, and connections to other functions

SeedRandom returns a RandomGeneratorState object with the new state:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-9csrlu
Out[1]=1

When a RandomGeneratorState object is used as a seed, explicit Method options are ignored:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-c2myn3
Out[1]=1

The state prior to seeding can be obtained from $RandomGeneratorState:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-1is60e
Out[1]=1

Use the current state:

In[2]:=2
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https://wolfram.com/xid/0i1irpdba-73407x
Out[2]=2

Generate a new seed and and use the new state:

In[3]:=3
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https://wolfram.com/xid/0i1irpdba-nmczcf
Out[3]=3

Seeding with the saved state reproduces the original sequence:

In[4]:=4
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https://wolfram.com/xid/0i1irpdba-qepnp8
Out[4]=4

BlockRandom effectively saves the random generator state and restores it at the end of the computation:

In[1]:=1
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https://wolfram.com/xid/0i1irpdba-llu
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0i1irpdba-txb
Out[2]=2
Wolfram Research (1988), SeedRandom, Wolfram Language function, https://reference.wolfram.com/language/ref/SeedRandom.html (updated 2020).
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Wolfram Research (1988), SeedRandom, Wolfram Language function, https://reference.wolfram.com/language/ref/SeedRandom.html (updated 2020).

Text

Wolfram Research (1988), SeedRandom, Wolfram Language function, https://reference.wolfram.com/language/ref/SeedRandom.html (updated 2020).

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Wolfram Research (1988), SeedRandom, Wolfram Language function, https://reference.wolfram.com/language/ref/SeedRandom.html (updated 2020).

CMS

Wolfram Language. 1988. "SeedRandom." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2020. https://reference.wolfram.com/language/ref/SeedRandom.html.

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Wolfram Language. 1988. "SeedRandom." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2020. https://reference.wolfram.com/language/ref/SeedRandom.html.

APA

Wolfram Language. (1988). SeedRandom. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/SeedRandom.html

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Wolfram Language. (1988). SeedRandom. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/SeedRandom.html

BibTeX

@misc{reference.wolfram_2025_seedrandom, author="Wolfram Research", title="{SeedRandom}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/SeedRandom.html}", note=[Accessed: 30-May-2025 ]}

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@misc{reference.wolfram_2025_seedrandom, author="Wolfram Research", title="{SeedRandom}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/SeedRandom.html}", note=[Accessed: 30-May-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_seedrandom, organization={Wolfram Research}, title={SeedRandom}, year={2020}, url={https://reference.wolfram.com/language/ref/SeedRandom.html}, note=[Accessed: 30-May-2025 ]}

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@online{reference.wolfram_2025_seedrandom, organization={Wolfram Research}, title={SeedRandom}, year={2020}, url={https://reference.wolfram.com/language/ref/SeedRandom.html}, note=[Accessed: 30-May-2025 ]}