*Do 6 Newton method iterations in cuberoot #550
Closed
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## dev/gfdl #550 +/- ##
============================================
- Coverage 37.20% 37.19% -0.01%
============================================
Files 271 271
Lines 80355 80341 -14
Branches 14985 14982 -3
============================================
- Hits 29894 29882 -12
+ Misses 44903 44902 -1
+ Partials 5558 5557 -1 ☔ View full report in Codecov by Sentry. |
Modified the cuberoot function to do 6 iterations with Newton's method, starting from the optimal first guess of (3/8)**(1/3). Following guidance from performance testing of the previous version, all convergence testing has been removed and the same number of iterations are applied regardless of the input value. The form of Newton's method used here does one division per iteration, but it is good at polishing the root to give an accurate final solution and by simply repeatedly using the same instructions it appears to optimize well. This commit changes answers at roundoff for code that uses the cuberoot function, so ideally this PR would be dealt with before the cuberoot becomes widely used.
Hallberg-NOAA
force-pushed
the
Newton_cuberoot
branch
from
533f049 to
3557f72
Compare
Hallberg-NOAA
changed the title
|
Handled in #544 |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Modified the
cuberoot()function to do 6 iterations with Newton's method, starting from the optimal first guess of (3/8)**(1/3). Following guidance from performance testing of the previous version (documented in the conversation surrounding #544), all convergence testing has been removed and the same number of iterations are applied regardless of the input value. The form of Newton's method used here does one division per iteration, but it is good at polishing the root to give an accurate final solution and by simply repeatedly using the same instructions it appears to optimize well. This commit changes answers at roundoff for code that uses thecuberoot()function, so ideally this PR would be dealt with before thecuberoot()becomes widely used.