TextMarshaller and TextUnmarshaller to ease transport of
unlimited precision rational numbers.
Fixes#7287.
Consists of encode and decode functions and two test
functions, one using JSON and one using XML. Each
verifies round trips for integers (rationals with
denominator == 1) and for fractional vaues.
LGTM=gri
R=gri, cookieo9, bradfitz, mtj
CC=golang-codereviews
https://golang.org/cl/61180043
I just added support for goto statements to my GopherJS project and now I am trying to get rid of my patches. These occurrences of goto however are a bit problematic:
GopherJS has to emulate gotos, so there is some performance drawback when doing so. In this case the drawback is major, since this is a core function of math/big which is called quite often. Additionally I can't see any reason here why the implementation with gotos should be preferred over my proposal.
That's why I would kindly ask to include this patch, even though it is functional equivalent to the existing code.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/55470046
Float32 and Float64 are now both created by taking the ratio
of two integers which are chosen to fit entirely into the
precision of the desired float type. The previous code
could cast a Float64 with more than 23 bits of ".99999"
into a Float32 of 1.0, which is not in [0,1).
Float32 went from 15 to 21 ns/op (but is now correct).
Fixes#6721.
R=golang-dev, iant, rsc
CC=golang-dev
https://golang.org/cl/22730043
Instead of writing out 0..n and then reading it
back, just use i when it is needed.
Wikipedia calls this the "inside-out" implementation:
http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle
This yields identical values to the previous
implementation, given the same seed. (Note that the
output from Example_rand is unchanged.)
2.8 GHz Intel Core i7, results very stable:
benchmark old ns/op new ns/op delta
BenchmarkPerm3 138 136 -1.45%
BenchmarkPerm30 825 803 -2.67%
Stock Raspberry Pi, minimum improvement out of three runs:
benchmark old ns/op new ns/op delta
BenchmarkPerm3 5774 5664 -1.91%
BenchmarkPerm30 32582 29381 -9.82%
R=golang-dev, dave, mtj, adg
CC=golang-dev
https://golang.org/cl/21030043
The routines in this file are dregs from a very early copy of the math API.
There are no Go prototypes and no non-amd64 implementations.
R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/15750046
Update #5305.
This handles the case where the nil pointers are inside a slice.
A top-level nil pointer is harder, maybe fundamentally broken by gob's model.
Thinking required.
However, a slice is the important case since people don't expect to be sending
top-level nils much, but they can arise easily in slices.
R=golang-dev, josharian, adg
CC=golang-dev
https://golang.org/cl/13042044
Phrases like "returns whether or not the image is opaque" could be
describing what the function does (it always returns, regardless of
the opacity) or what it returns (a boolean indicating the opacity).
Even when the "or not" is missing, the phrasing is bizarre.
Go with "reports whether", which is still clunky but at least makes
it clear we're talking about the return value.
These were edited by hand. A few were cleaned up in other ways.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/11699043
This patch resulted from a bit of quick optimisation in response to a
golang-nuts post. It looks like one could save a couple other copies in
this function, but this addresses the inner loop and is fairly simple.
benchmark old ns/op new ns/op delta
BenchmarkGCD10x10 1964 1711 -12.88%
BenchmarkGCD10x100 2019 1736 -14.02%
BenchmarkGCD10x1000 2471 2171 -12.14%
BenchmarkGCD10x10000 6040 5778 -4.34%
BenchmarkGCD10x100000 43204 43025 -0.41%
BenchmarkGCD100x100 11004 8520 -22.57%
BenchmarkGCD100x1000 11820 9446 -20.08%
BenchmarkGCD100x10000 23846 21382 -10.33%
BenchmarkGCD100x100000 133691 131505 -1.64%
BenchmarkGCD1000x1000 120041 95591 -20.37%
BenchmarkGCD1000x10000 136887 113600 -17.01%
BenchmarkGCD1000x100000 295370 273912 -7.26%
BenchmarkGCD10000x10000 2556126 2205198 -13.73%
BenchmarkGCD10000x100000 3159512 2808038 -11.12%
BenchmarkGCD100000x100000 150543094 139986045 -7.01%
R=gri, remyoudompheng
CC=bradfitz, gobot, golang-dev, gri
https://golang.org/cl/9424043
- comment fixes
- s/z/x/ in (*rat).Float64 to match convention for functions
returning a non-*Rat
- minor test output tweaking
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8327044
The edit makes Hypot's description match the form
used in the other routines in this package.
R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8003046
Added tests, using input data from strconv.ParseFloat.
Thanks to rsc for most of the test code.
math/big could use some good package-level documentation.
R=remyoudompheng, rsc
CC=golang-dev
https://golang.org/cl/6930059
bytes.Equal is simpler to read and should also be faster because
of short-circuiting and assembly implementations.
Change generated automatically using:
gofmt -r 'bytes.Compare(a, b) == 0 -> bytes.Equal(a, b)'
gofmt -r 'bytes.Compare(a, b) != 0 -> !bytes.Equal(a, b)'
R=golang-dev, dave, adg, rsc
CC=golang-dev
https://golang.org/cl/7038051
This guarantees that powers of two return exact answers.
We could do a multiprecision approximation for the
rest of the answer too, but this seems like it should be
good enough.
Fixes#4567.
R=golang-dev, iant, remyoudompheng
CC=golang-dev
https://golang.org/cl/6943074
Implementation is mostly identical to passing a non-negative int64 to
SetInt64, and calling Int64 with a non-negative value in the *Int.
Fixes#4389.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6929048
This changes the output of
rand.Seed(0)
perm := rand.Perm(100)
When giving the same seeds to Go 1.0 and Go 1.1 programs
I would like them to generate the same random numbers.
««« original CL description
math/rand: remove noop iteration in Perm
The first iteration always do `m[0], m[0] = m[0], m[0]`, because
`rand.Intn(1)` is 0.
fun note: IIRC in TAOCP version of this algorithm, `i` goes
backward (n-1->1), meaning that the "already" shuffled part of the
array is never altered betweens iterations, while in the current
implementation the "not-yet" shuffled part of the array is
conserved between iterations.
R=golang-dev
CC=golang-dev
https://golang.org/cl/6845121
»»»
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6905049
The first iteration always do `m[0], m[0] = m[0], m[0]`, because
`rand.Intn(1)` is 0.
fun note: IIRC in TAOCP version of this algorithm, `i` goes
backward (n-1->1), meaning that the "already" shuffled part of the
array is never altered betweens iterations, while in the current
implementation the "not-yet" shuffled part of the array is
conserved between iterations.
R=golang-dev
CC=golang-dev
https://golang.org/cl/6845121
A 4-bit window is convenient because 4 divides both 32 and 64,
therefore we never have a window spanning words of the exponent.
Additionaly, the benefit of a 5-bit window is only 2.6% at 1024-bits
and 3.3% at 2048-bits.
This code is still not constant time, however.
benchmark old ns/op new ns/op delta
BenchmarkRSA2048Decrypt 17108590 11180370 -34.65%
Benchmark3PrimeRSA2048Decrypt 13003720 7680390 -40.94%
R=gri
CC=golang-dev
https://golang.org/cl/6716048
- always return 1 for y <= 0
- document that the sign of m is ignored
- protect against div-0 panics by treating
m == 0 the same way as m == nil
- added extra tests
Fixes#4239.
R=agl, remyoudompheng, agl
CC=golang-dev
https://golang.org/cl/6724046
The assembly offsets were converted mechanically using
code.google.com/p/rsc/cmd/asmlint. The instruction
changes were done by hand.
Fixes#2188.
R=iant, r, bradfitz, remyoudompheng
CC=golang-dev
https://golang.org/cl/6550058
