diff options
| author | Mark Dickinson <dickinsm@gmail.com> | 2019-05-18 11:29:50 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2019-05-18 11:29:50 (GMT) |
| commit | 73934b9da07daefb203e7d26089e7486a1ce4fdf (patch) | |
| tree | 6d5f9d2f8bd86dbd219685a3e6124af44a158811 /Doc/library | |
| parent | 410759fba80aded5247b693c60745aa16906f3bb (diff) | |
| download | cpython-73934b9da07daefb203e7d26089e7486a1ce4fdf.zip cpython-73934b9da07daefb203e7d26089e7486a1ce4fdf.tar.gz cpython-73934b9da07daefb203e7d26089e7486a1ce4fdf.tar.bz2 | |
bpo-36887: add math.isqrt (GH-13244)
* Add math.isqrt function computing the integer square root.
* Code cleanup: remove redundant comments, rename some variables.
* Tighten up code a bit more; use Py_XDECREF to simplify error handling.
* Update Modules/mathmodule.c
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>
* Update Modules/mathmodule.c
Use real argument clinic type instead of an alias
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>
* Add proof sketch
* Updates from review.
* Correct and expand documentation.
* Fix bad reference handling on error; make some variables block-local; other tidying.
* Style and consistency fixes.
* Add missing error check; don't try to DECREF a NULL a
* Simplify some error returns.
* Another two test cases:
- clarify that floats are rejected even if they happen to be
squares of small integers
- TypeError beats ValueError for a negative float
* Documentation and markup improvements; thanks Serhiy for the suggestions!
* Cleaner Misc/NEWS entry wording.
* Clean up (with one fix) to the algorithm explanation and proof.
Diffstat (limited to 'Doc/library')
| -rw-r--r-- | Doc/library/math.rst | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Doc/library/math.rst b/Doc/library/math.rst index 49f932d..bf660ae 100644 --- a/Doc/library/math.rst +++ b/Doc/library/math.rst @@ -166,6 +166,20 @@ Number-theoretic and representation functions Return ``True`` if *x* is a NaN (not a number), and ``False`` otherwise. +.. function:: isqrt(n) + + Return the integer square root of the nonnegative integer *n*. This is the + floor of the exact square root of *n*, or equivalently the greatest integer + *a* such that *a*\ ² |nbsp| ≤ |nbsp| *n*. + + For some applications, it may be more convenient to have the least integer + *a* such that *n* |nbsp| ≤ |nbsp| *a*\ ², or in other words the ceiling of + the exact square root of *n*. For positive *n*, this can be computed using + ``a = 1 + isqrt(n - 1)``. + + .. versionadded:: 3.8 + + .. function:: ldexp(x, i) Return ``x * (2**i)``. This is essentially the inverse of function @@ -538,3 +552,6 @@ Constants Module :mod:`cmath` Complex number versions of many of these functions. + +.. |nbsp| unicode:: 0xA0 + :trim: |