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docs: adding skeleton README.md files for all vlib modules (#13034)

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jeffmikels
2022-01-05 11:06:08 -05:00
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vlib/rand/README.md
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@@ -1,4 +1,4 @@
# Quickstart
# Description
The V `rand` module provides two main ways in which users can generate pseudorandom numbers:
@@ -29,27 +29,27 @@ For arrays, see `rand.util`.
# General Background
A PRNG is a Pseudo Random Number Generator.
Computers cannot generate truly random numbers without an external source of noise or entropy.
We can use algorithms to generate sequences of seemingly random numbers,
but their outputs will always be deterministic.
A PRNG is a Pseudo Random Number Generator.
Computers cannot generate truly random numbers without an external source of noise or entropy.
We can use algorithms to generate sequences of seemingly random numbers,
but their outputs will always be deterministic.
This is often useful for simulations that need the same starting seed.
If you need truly random numbers that are going to be used for cryptography,
If you need truly random numbers that are going to be used for cryptography,
use the `crypto.rand` module.
# Guaranteed functions
The following 21 functions are guaranteed to be supported by `rand`
The following 21 functions are guaranteed to be supported by `rand`
as well as the individual PRNGs.
- `seed(seed_data)` where `seed_data` is an array of `u32` values.
Different generators require different number of bits as the initial seed.
The smallest is 32-bits, required by `sys.SysRNG`.
- `seed(seed_data)` where `seed_data` is an array of `u32` values.
Different generators require different number of bits as the initial seed.
The smallest is 32-bits, required by `sys.SysRNG`.
Most others require 64-bits or 2 `u32` values.
- `u32()`, `u64()`, `int()`, `i64()`, `f32()`, `f64()`
- `u32n(max)`, `u64n(max)`, `intn(max)`, `i64n(max)`, `f32n(max)`, `f64n(max)`
- `u32_in_range(min, max)`, `u64_in_range(min, max)`, `int_in_range(min, max)`,
- `u32_in_range(min, max)`, `u64_in_range(min, max)`, `int_in_range(min, max)`,
`i64_in_range(min, max)`, `f32_in_range(min, max)`, `f64_in_range(min, max)`
- `int31()`, `int63()`
@@ -59,7 +59,7 @@ PRNG, you can can change the global RNG to do so.
# Seeding Functions
All the generators are time-seeded.
All the generators are time-seeded.
The helper functions publicly available in `rand.seed` module are:
1. `time_seed_array()` - returns a `[]u32` that can be directly plugged into the `seed()` functions.
@@ -69,8 +69,8 @@ The helper functions publicly available in `rand.seed` module are:
# Caveats
Note that the `sys.SysRNG` struct (in the C backend) uses `C.srand()` which sets the seed globally.
Consequently, all instances of the RNG will be affected.
This problem does not arise for the other RNGs.
Consequently, all instances of the RNG will be affected.
This problem does not arise for the other RNGs.
A workaround (if you _must_ use the libc RNG) is to:
1. Seed the first instance.
@@ -83,5 +83,5 @@ A workaround (if you _must_ use the libc RNG) is to:
Please note that [math interval](https://en.wikipedia.org/wiki/Interval_(mathematics)#Including_or_excluding_endpoints) notation is used throughout
the function documentation to denote what numbers ranges include.
An example of `[0, max)` thus denotes a range with all posible values
An example of `[0, max)` thus denotes a range with all posible values
between `0` and `max` **including** 0 but **excluding** `max`.