'math.randomseed()' sets a somewhat random seed

When called with no arguments, 'math.randomseed' uses time and ASLR
to generate a somewhat random seed. the initial seed when Lua starts
is generated this way.
This commit is contained in:
Roberto Ierusalimschy
2019-03-13 14:47:48 -03:00
parent c5feac2b5e
commit 9eca305e75
3 changed files with 36 additions and 20 deletions

View File

@@ -7643,14 +7643,10 @@ is equivalent to @T{math.random(1,n)}.
The call @T{math.random(0)} produces an integer with
all bits (pseudo)random.
Lua initializes its pseudo-random generator with
a weak attempt for ``randomness'',
Lua initializes its pseudo-random generator with the equivalent of
a call to @Lid{math.randomseed} with no arguments,
so that @id{math.random} should generate
different sequences of results each time the program runs.
To ensure a required level of randomness to the initial state
(or contrarily, to have a deterministic sequence,
for instance when debugging a program),
you should call @Lid{math.randomseed} explicitly.
The results from this function have good statistical qualities,
but they are not cryptographically secure.
@@ -7660,14 +7656,23 @@ some number of previous results.)
}
@LibEntry{math.randomseed (x [, y])|
@LibEntry{math.randomseed ([x [, y]])|
The integer parameters @id{x} and @id{y} are
concatenated into a 128-bit @Q{seed} that
When called with at least one argument,
the integer parameters @id{x} and @id{y} are
concatenated into a 128-bit @emphx{seed} that
is used to reinitialize the pseudo-random generator;
equal seeds produce equal sequences of numbers.
The default for @id{y} is zero.
When called with no arguments,
Lua generates a seed with
a weak attempt for randomness.
To ensure a required level of randomness to the initial state
(or contrarily, to have a deterministic sequence,
for instance when debugging a program),
you should call @Lid{math.randomseed} with explicit arguments.
}
@LibEntry{math.sin (x)|