Implements the [Gamma distribution](https://en.wikipedia.org/wiki/Gamma_distribution), using the algorithm described by Marsaglia & Tsang 2000[1]. I added tests checking that the mean and variance of this implementation is as expected for a range of values of the parameters in 5d87c00a0f (they pass locally, but obviously won't even build on Travis until this is merged).
Also, moves `std::rand::distributions` to a subfolder, and performs a minor clean-up of the benchmarking (makes the number of iterations shared by the whole `std::rand` subtree).
[1]: George Marsaglia and Wai Wan Tsang. 2000. "A Simple Method for Generating Gamma Variables" *ACM Trans. Math. Softw.* 26, 3 (September 2000), 363-372. DOI:[10.1145/358407.358414](http://doi.acm.org/10.1145/358407.358414).
Previously we were actually overwriting `CFG_{HOST,TARGET,BUILD}` with `CFG_{HOST,TARGET,BUILD}_TRIPLE(S)` since configure tested for the legacy one by checking if it was empty which would never be the case. That meant it wouldn't split up multiple triples and just treat it as one long triple.
This pull also fixes the rules that were changed when librustuv was added to use the right CFG_ vars and removes the legacy flags.
Tests now have the same name as the test that they're running (to allow for
easier diagnosing of failure sources), and the main task is now specially named
`<main>` instead of `<unnamed>`.
Closes#10195Closes#10073
This takes the last reforms on the `Option` type and applies them to `Result` too. For that, I reordered and grouped the functions in both modules, and also did some refactorings:
- Added `as_ref` and `as_mut` adapters to `Result`.
- Renamed `Result::map_move` to `Result::map` (same for `_err` variant), deleted other map functions.
- Made the `.expect()` methods be generic over anything you can
fail with.
- Updated some doc comments to the line doc comment style
- Cleaned up and extended standard trait implementations on `Option` and `Result`
- Removed legacy implementations in the `option` and `result` module
Tests now have the same name as the test that they're running (to allow for
easier diagnosing of failure sources), and the main task is now specially named
<main> instead of <unnamed>.
Closes#10195Closes#10073
The previous method was unsound because you could very easily create two mutable
pointers which alias the same location (not sound behavior). This hides the
function which does so and then exports an explicit flush() function (with
documentation about how it works).
Cleaned up the source in a few places
Renamed `map_move` to `map`, removed other `map` methods
Added `as_ref` and `as_mut` adapters to `Result`
Added `fmt::Default` impl
Fix the implementation of `std::rand::Rng::fill_bytes()` for
`std::rand::reseeding::ReseedingRng` to call the `fill_bytes()` method
of the underlying RNG rather than itself, which causes infinite
recursion.
Fixes#10202.
The code was using (in the notation of Doornik 2005) `f(x_{i+1}) -
f(x_{i+2})` rather than `f(x_i) - f(x_{i+1})`. This corrects that, and
removes the F_DIFF tables which caused this problem in the first place.
They `F_DIFF` tables are a micro-optimisation (in theory, they could
easily be a micro-pessimisation): that `if` gets hit about 1% of the
time for Exp/Normal, and the rest of the condition involves RNG calls
and a floating point `exp`, so it is unlikely that saving a single FP
subtraction will be very useful (especially as more tables means more
memory reads and higher cache pressure, as well as taking up space in
the binary (although only ~2k in this case)).
Closes#10084. Notably, unlike that issue suggests, this wasn't a
problem with the Exp tables. It affected Normal too, but since it is
symmetric, there was no bias in the mean (as the bias was equal on the
positive and negative sides and so cancelled out) but it was visible as
a variance slightly lower than it should be.
New plot:
I've started writing some tests in [huonw/random-tests](https://github.com/huonw/random-tests) (not in the main repo because they can and do fail occasionally, due to randomness, but it is on Travis and Rust-CI so it will hopefully track the language), unsurprisingly, they're [currently failing](https://travis-ci.org/huonw/random-tests/builds/13313987) (note that both exp and norm are failing, the former due to both mean and variance the latter due to just variance), but pass at the 0.01 level reliably with this change.
(Currently the only test is essentially a quantitative version of the plots I've been showing, which is run on the `f64` `Rand` instance (uniform 0 to 1), and the Normal and Exp distributions.)
The previous method was unsound because you could very easily create two mutable
pointers which alias the same location (not sound behavior). This hides the
function which does so and then exports an explicit flush() function (with
documentation about how it works).
Fix the implementation of `std::rand::Rng::fill_bytes()` for
`std::rand::reseeding::ReseedingRng` to call the `fill_bytes()` method
of the underlying RNG rather than itself, which causes infinite
recursion.
Fixes#10202.
This extension can be used to concatenate string literals at compile time. C has
this useful ability when placing string literals lexically next to one another,
but this needs to be handled at the syntax extension level to recursively expand
macros.
The major use case for this is something like:
macro_rules! mylog( ($fmt:expr $($arg:tt)*) => {
error2!(concat!(file!(), ":", line!(), " - ", $fmt) $($arg)*);
})
Where the mylog macro will automatically prepend the filename/line number to the
beginning of every log message.
This extension can be used to concatenate string literals at compile time. C has
this useful ability when placing string literals lexically next to one another,
but this needs to be handled at the syntax extension level to recursively expand
macros.
The major use case for this is something like:
macro_rules! mylog( ($fmt:expr $($arg:tt)*) => {
error2!(concat!(file!(), ":", line!(), " - ", $fmt) $($arg)*);
})
Where the mylog macro will automatically prepend the filename/line number to the
beginning of every log message.
To keep consistency with the word "borrowing" I suppose an alternate way to write this could be "Having an object borrow an immutable pointer freezes it and prevents mutation".
The code was using (in the notation of Doornik 2005) `f(x_{i+1}) -
f(x_{i+2})` rather than `f(x_i) - f(x_{i+1})`. This corrects that, and
removes the F_DIFF tables which caused this problem in the first place.
They `F_DIFF` tables are a micro-optimisation (in theory, they could
easily be a micro-pessimisation): that `if` gets hit about 1% of the
time for Exp/Normal, and the rest of the condition involves RNG calls
and a floating point `exp`, so it is unlikely that saving a single FP
subtraction will be very useful (especially as more tables means more
memory reads and higher cache pressure, as well as taking up space in
the binary (although only ~2k in this case)).
Closes#10084. Notably, unlike that issue suggests, this wasn't a
problem with the Exp tables. It affected Normal too, but since it is
symmetric, there was no bias in the mean (as the bias was equal on the
positive and negative sides and so cancelled out) but it was visible as
a variance slightly lower than it should be.
- `begin_unwind` and `fail!` is now generic over any `T: Any + Send`.
- Every value you fail with gets boxed as an `~Any`.
- Because of implementation issues, `&'static str` and `~str` are still
handled specially behind the scenes.
- Changed the big macro source string in libsyntax to a raw string
literal, and enabled doc comments there.
- `begin_unwind` is now generic over any `T: Any + Send`.
- Every value you fail with gets boxed as an `~Any`.
- Because of implementation details, `&'static str` and `~str` are still
handled specially behind the scenes.
- Changed the big macro source string in libsyntax to a raw string
literal, and enabled doc comments there.
