Skip to content

Fix ln() rounding up on a result just below a rounding tie #261

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
spokodev wants to merge 1 commit into
base: master
Choose a base branch
from
+17 −4
Open

Fix ln() rounding up on a result just below a rounding tie #261

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 4 additions & 2 deletions decimal.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2595,11 +2595,13 @@
if (i == 0) rd = rd / 1000 | 0;
else if (i == 1) rd = rd / 100 | 0;
else if (i == 2) rd = rd / 10 | 0;
r = (repeating || rm < 4) && rd == 9999 || !repeating && rm > 3 && rd == 4999;
r = (repeating || rm < 4) && rd == 9999 || !repeating && rm > 3 && rd == 4999
|| rd == 5000 || rd == 0;
} else {
r = ((repeating || rm < 4) && rd + 1 == k ||
(!repeating && rm > 3) && rd + 1 == k / 2) &&
(d[di + 1] / k / 1000 | 0) == mathpow(10, i - 3) - 1;
(d[di + 1] / k / 1000 | 0) == mathpow(10, i - 3) - 1
|| (rd == k / 2 || rd == 0) && (d[di + 1] / k / 1000 | 0) == 0;
}
}

Expand Down
6 changes: 4 additions & 2 deletions decimal.mjs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2591,11 +2591,13 @@ function checkRoundingDigits(d, i, rm, repeating) {
if (i == 0) rd = rd / 1000 | 0;
else if (i == 1) rd = rd / 100 | 0;
else if (i == 2) rd = rd / 10 | 0;
r = (repeating || rm < 4) && rd == 9999 || !repeating && rm > 3 && rd == 4999;
r = (repeating || rm < 4) && rd == 9999 || !repeating && rm > 3 && rd == 4999
|| rd == 5000 || rd == 0;
} else {
r = ((repeating || rm < 4) && rd + 1 == k ||
(!repeating && rm > 3) && rd + 1 == k / 2) &&
(d[di + 1] / k / 1000 | 0) == mathpow(10, i - 3) - 1;
(d[di + 1] / k / 1000 | 0) == mathpow(10, i - 3) - 1
|| (rd == k / 2 || rd == 0) && (d[di + 1] / k / 1000 | 0) == 0;
}
}

Expand Down
9 changes: 9 additions & 0 deletions test/modules/ln.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,15 @@ T('ln', function () {
t('NaN', String(Math.log(NaN)), 40, 4);
t('2.7182818284590452353602874713526624977572', '1', 39, 4);

// Correctly-rounded ln where the result lands just below a rounding tie
// (...d 4999...): these rounded up instead of down before the guard-digit
// fix in checkRoundingDigits.
t('4.25914212183600678912449997353532582823393815', '1.4490677601509316343', 20, 4);
t('1.6852358445909596506369573334700403721376594', '0.52190552112613867979', 20, 4);
t('147.901327174696092190385346999167895276772254', '4.9965453431362365587', 20, 4);
t('7.65606302212512952930223042181358382147654373', '2.0354978858468052277', 20, 4);
t('24.7812098757520159815273195615677780988161707', '3.2100856996964392732', 20, 4);

t('91247532.65728', '18.3290865106890306', 19, 1);
t('727579403.9', '20.40523369730819818291393006', 28, 3);
t('419065154.52076499608', '19.8535369658470908', 19, 2);
Expand Down