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Katie Hockman e491c6eea9 math/big: fix comment in divRecursiveStep
There appears to be a typo in the description of
the recursive division algorithm.

Two things seem suspicious with the original comment:
  1. It is talking about choosing s, but s doesn't
     appear anywhere in the equation.
  2. The math in the equation is incorrect.

Where
  B = len(v)/2
  s = B - 1

Proof that it is incorrect:
    len(v) - B >= B + 1
    len(v) - len(v)/2 >= len(v)/2 + 1

    This doesn't hold if len(v) is even, e.g. 10:
    10 - 10/2 >= 10/2 + 1
    10 - 5 >= 5 + 1
    5 >= 6  // this is false

The new equation will be the following,
which will be mathematically correct:
    len(v) - s >= B + 1
    len(v) - (len(v)/2 - 1) >= len(v)/2 + 1
    len(v) - len(v)/2 + 1 >= len(v)/2 + 1
    len(v) - len(v)/2 >= len(v)/2

    This holds if len(v) is even or odd.

    e.g. 10
    10 - 10/2 >= 10/2
    10 - 5 >= 5
    5 >= 5

    e.g. 11
    11 - 11/2 >= 11/2
    11 - 5 >= 5
    6 >= 5

Change-Id: If77ce09286cf7038637b5dfd0fb7d4f828023f56
Reviewed-on: https://go-review.googlesource.com/c/go/+/287372
Run-TryBot: Katie Hockman <katie@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Trust: Katie Hockman <katie@golang.org>
2021-02-03 15:04:02 +00:00
.github .github: add link to questions in ISSUE_TEMPLATE 2020-01-06 17:05:31 +00:00
api api/go1.16: add go/build/constraint APIs 2021-01-27 21:11:22 +00:00
doc spec: improve the example in Type assertions section 2021-02-02 16:35:53 +00:00
lib/time lib/time, time/tzdata: update tzdata to 2021a 2021-01-25 16:08:46 +00:00
misc cmd/link: don't decode type symbol in shared library in deadcode 2021-02-02 16:00:58 +00:00
src math/big: fix comment in divRecursiveStep 2021-02-03 15:04:02 +00:00
test test: fix incorrectly laid out instructions in issue11656.go 2021-02-01 21:38:01 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
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AUTHORS A+C: add Kush Patel (corporate CLA for Hootsuite Inc) 2020-07-08 00:10:44 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS CONTRIBUTORS: update for the Go 1.15 release 2020-08-10 21:51:48 +00:00
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