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57 commits

Author SHA1 Message Date
nicoo
bd4d6fcac5 factor: Split the CLI and I/O code off the factoring logic 2020-07-05 00:05:45 +02:00
nicoo
abf579975c factor::miller_rabin: Fix bug in primality test 
Introduced in 6b9585b1 (#1525: Performance improvements for `factor`).
Closes #1556
 2020-06-23 16:19:16 +02:00
nicoo
c5c86b00e9 factor::miller_rabin: Add tests reproducing #1556 2020-06-23 16:14:52 +02:00
nicoo
8e040bbf1a factor::table: Optimise the size of the precomputed table 
A too-large precomputed table actually slows down the program: we spend
time fetching it from disk and from memory (into the CPU's cache), and
larger prime factors are more unlikely to occur in random integers (prime p
occurs with probability ~1/p when sampling 64b numbers uniformly-at-random)

The new value was chosen after measuring the execution time (for all
integers between 2 and 10⁷) for a broad set of values:

| n    | time (s) |
|------|----------|
| 16   | 40.84    |
| 32   | 34.491   |
| 64   | 29.044   |
| 128  | 25.121   |
| 192  | 23.98    |
| 256  | 23.102   |
| 256  | 24.93    |
| 272  | 23.57    |
| 288  | 23.85    |
| 304  | 23.91    |
| 320  | 23.24    |
| 329  | 23.45    |
| 336  | 23.55    |
| 352  | 23.09    |
| 368  | 23.65    |
| 384  | 23.32    |
| 384  | 23.36    |
| 400  | 23.30    |
| 416  | 23.38    |
| 432  | 23.42    |
| 448  | 23.95    |
| 448  | 24.00    |
| 464  | 23.81    |
| 480  | 23.55    |
| 496  | 24.10    |
| 512  | 24.101   |
| 512  | 24.23    |
| 1027 | 29.864   |
 2020-06-20 22:22:55 +02:00
nicoo
9d992b77b2 factor: Keep the primes table size in a single place 2020-06-20 22:22:55 +02:00
nicoo
b956e632e1 factor::table: Coalesce accesses to the factors table 
~5.6% faster
 2020-06-20 22:22:55 +02:00
nicoo
0518e06053 factor::rho: Minor refactor for readability 2020-06-20 10:39:56 +02:00
nicoo
dacee413db factor::rho: Refactor to avoid unnecessary allocations 2020-06-20 10:39:56 +02:00
nicoo
71e1c52920 factor::Factors: Rename new() to one() 2020-06-20 10:39:56 +02:00
nicoo
45a1408fb0 fixup! factor: Add test exhibiting a bug in ρ 2020-06-19 15:28:01 +02:00
nicoo
9fe3de72f2 factor::rho: Fix very-unlikely bug (resulting in assertion failure) 
This bug can only be triggered when:
- the Miller-Rabin test produces a divisor `d` (rare) ;
- n / d is prime.
 2020-06-19 13:51:29 +02:00
nicoo
9eb944b6b9 factor: Add test exhibiting a bug in ρ 
The test is repeated 20 times to make it overwhelmingly-likely to fail
(the bug itself is only triggered rarely)
 2020-06-19 13:48:00 +02:00
nicoo
3a90e31307 factor::numeric::inv_mod_u64: Provide a more-helpful error message 2020-06-19 13:39:42 +02:00
nicoo
ef12991ee7 factors: Avoid repeatedly locking and flushing stdout 
By default, stdout's LineWriter results one syscall per line, i.e. a billion
syscalls when factoring a billion numbers...

Buffering the output yields a ~28% speedup.
 2020-06-18 16:45:40 -07:00
nicoo
2869248318 factor::Factors: Use a tree-based map internally 
This eliminate the need for sorting the prime factors for display.
25% performance improvement after the changes from factor/montgomery.
 2020-06-18 16:44:08 -07:00
nicoo
4b4d11b61a
factor: Add/update copyright notices as necessary (#1546) 2020-06-18 21:38:28 +02:00
Alex Lyon
6105cce69a
Merge pull request #1529 from nbraud/factor/montgomery 
factor: Faster modular arithmetic with the Montgomery transform
 2020-06-18 09:19:12 -07:00
nicoo
fb08d9ff9e factor::numeric::Montgomery::add: Deal with rare overflow case 2020-06-18 14:32:58 +02:00
nicoo
d1470dadf8 factor::numeric::gcd: Silence the (erroneous) dead code lint 2020-06-16 15:45:10 +02:00
nicoo
334e02786d factor: Run cargo fmt 2020-06-16 15:43:25 +02:00
Alex Lyon
110d6844ad
Use an iterator over OsString for uumain() 
Additionally, restructure `uname` so that we don't need to find the
iterator's length.
 2020-06-16 03:28:02 -05:00
nicoo
f1788d9e70 fixup! factor::numeric::Montgomery: Fix overflow bug 2020-06-16 01:17:16 +02:00
nicoo
4851619d62 factor::miller_rabin: Avoid repeatedly transforming 1 and -1 
Approx. 25% speedup
 2020-06-15 23:05:31 +02:00
nicoo
cb6051c580 factor::numeric::Montgomery: Fix overflow bug 2020-06-15 22:40:57 +02:00
nicoo
2238065c9d factor::numeric: Simplify Montgomery (remove superfluous Wrapping) 2020-06-15 19:18:34 +02:00
nicoo
19a0645a0a factor::numeric: Simplify inv_mod_u64 
Just call `u64::wrapping_{mul,sub}` instead of (de)constructing Wrapping<u64>
values.
 2020-06-15 19:18:34 +02:00
nicoo
918035e01e factor: Fix for old Rust 2020-06-15 19:18:34 +02:00
nicoo
f84d0f9398 factor::Factors::add: Make the precondition check a debug_assert 2020-06-15 19:18:34 +02:00
nicoo
33e18b4cd3 factor::numeric::Montgomery: Add debug assertions 
In debug mode, checks that all arithmetic operations coincide with the
plain-u64 versions, as long as the latter does not overflow.
 2020-06-15 19:18:34 +02:00
nicoo
8a4d0d30ad factor::numeric: Implement Montgomery's transform 
This is a facter way to perform arithmetic mod n, when n is odd and a 64b
number.
 2020-06-15 19:18:29 +02:00
nicoo
e91155519a factor::factor: Add integration tests 2020-06-15 19:10:16 +02:00
nicoo
bada7530fb factor::miller_rabin: Add tests 2020-06-15 19:10:16 +02:00
Roy Ivy III
fbbd881ca9 docs ~ reduce sub-crate meta-information keywords to the maximum of five 2020-05-31 15:48:54 -05:00
Roy Ivy III
f82de13847 docs ~ spell-check repairs and addition of exceptions 2020-05-30 01:36:02 -05:00
Roy Ivy III
ea3235c7e2 change ~ new_coreopts!() => app!() (from uucore v0.0.4) 2020-05-29 22:59:48 -05:00
Roy Ivy III
6f465eeb9f deps ~ update utils to uucore/uucore_procs v0.0.4 2020-05-29 22:59:48 -05:00
Roy Ivy III
d4aa3a2231 fix 'edition="2018"' module import errors 
- ref: <https://users.rust-lang.org/t/imports-can-only-refer-to-extern-crate-names/24388> @@ <https://archive.is/iCaXp>
 2020-05-29 22:59:47 -05:00
Roy Ivy III
d70db1f7d2 docs ~ improve/update sub-crate meta information 2020-05-29 22:59:47 -05:00
Roy Ivy III
db2e950918 change ~ make all sub-crates independent 2020-05-29 22:59:40 -05:00
Nicolas Braud-Santoni
4c3682aec7
factor::Factors::add: Split up to work without NLL 
Co-authored-by: Roy Ivy III <rivy.dev@gmail.com>
 2020-05-24 19:14:37 +02:00
nicoo
36a2948959 factor::miller_rabin: Avoid unecessary exponentiation 
Instead of computing a^r and a^(n-1) = a^(r 2ⁱ) separately,
compute the latter by repeatedly squaring the former.

33.6% performance improvement
 2020-05-24 19:10:34 +02:00
nicoo
543c7b941a factor::rho: Small refactor 2020-05-24 19:10:29 +02:00
nicoo
30fd6a0309 factor::numeric: Replace lose functions with an Arithmetic trait 2020-05-24 18:16:21 +02:00
nicoo
29eb8fd77b format: Make clippy happy 2020-05-24 17:06:19 +02:00
nicoo
8241037690 factor::miller_rabin: Extract dividers from the primality test 
Another 36% improvement.
 2020-05-24 15:41:23 +02:00
nicoo
6b9585b1dc factor::miller_rabbin: Refactor before extracting dividers 
Replace iterated division with u64::trailing_zeros, hoist the selection of `mul`
out of the loop, another cool 49.5% runtime improvement.
 2020-05-24 15:41:23 +02:00
nicoo
e3ecc81d97 factor: Move the Miller-Rabin primality test to its own module. 2020-05-24 15:41:23 +02:00
nicoo
74054feb94 factor::factor: Remove extraneous call to the primality test 
Another 6.97% runtime improvement
 2020-05-24 15:41:23 +02:00
nicoo
e1a6dbe619 factor::table: Remove obsolete, commented code 2020-05-24 15:41:23 +02:00
nicoo
169740629b factor::table: Remove extraneous calls to the primality test 
50% performance improvement on factoring all numbers between 2 and 10⁶.
 2020-05-24 15:41:23 +02:00