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Integrate cube roots of two linears beside a power of a third, and a root over a power of x (b + c x) - #1976

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integrate-cube-roots-of-two-linears-and-a-root-over-x-b-cx
Oct 20, 2026
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@Rafael-SOWNet Rafael-SOWNet commented Oct 20, 2026 •

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Two seams of Rubi's family 1:

  • (a + b x)^(1/3) (c + d x)^(2/3)/(e + f x)^2 and its kin in 1.1.1.3 are rational in t = (a + b x)^(1/3)/(c + d x)^(1/3) wherever the two powers add to a whole number, for every complex x. The substitution that reached it left a binomial in t^3 spelled as k (b - d t^3) + f (c t^3 - a), and the rational rules ran out of time on it. It is now written as that binomial from the coefficients, each compound coefficient named and written back into the answer, where the denominator in t is not squarefree.
  • (A + B x) sqrt(d + e x)/(b x + c x^2)^3 and its kin in 1.2.1.3 are rational in t = sqrt(d + e x) with the quadratic kept as x (b + c x). The substitution that reached it, late in the chain, multiplied the quadratic out. It is asked that way now, with the root above the bar and a third power or higher.

Each declines where its linears share a root, decided as a value.

Measured on 8a1ef454, branch against master:

Run Problems Master Branch
Pocket: Rubi's 1.x 2,824 2,777 solved 2,794 solved
Family 1, 40 a file 1,381 1,362 1,362
Family 0, whole 1,814 1,789 1,789
Families 2 to 8, sampled 2,410 2,362 2,359

Re-run alone on both builds, 19 problems go from timed out to answered, in 0.2–2.0 s: Rubi's 1.1.1.3:3415–3418, 3425–3427, 3439, 3440 and 3472–3474; 1.2.1.2:447; and 1.2.1.3:1394–1398. 1.2.1.2:444 goes from 21 s to 0.4 s.

The three sampled problems that master answered and the branch did not, 3.2.1:292, 6.4.2:50 and 6.6.1:25, are the ones master answers in 17–24 s, against a 5 s budget. Re-run alone, both builds answer 6.6.1:25. At a 60 s budget, both answer the other two and allocate the same to 0.0001% (34.2 GB and 28.4 GB), so the branch does not reach them. None of the problems answered on both builds allocates more on the branch. No run had a wrong answer.

The two new test classes differentiate the answers back. BREAKING-CHANGES.md has the entry, with the 2.5.0 column measured on v2.5.0.

Part of #233.

🤖 Generated with Claude Code

https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

…root over a power of x (b + c x)

(a + b x)^(1/3) (c + d x)^(2/3)/(e + f x)^2 and its kin in Rubi's 1.1.1.3
are rational in t = (a + b x)^(1/3)/(c + d x)^(1/3). The substitution that
reached it left a binomial in t^3 spelled as k (b - d t^3) + f (c t^3 - a),
and the rational rules ran out of time on it. It is written as that binomial
now, with the compound coefficients named, where the denominator in t is not
squarefree.

(A + B x) sqrt(d + e x)/(b x + c x^2)^3 and its kin in 1.2.1.3 are rational
in t = sqrt(d + e x) with the quadratic kept as x (b + c x). The substitution
that reached it late in the chain multiplied it out. Both rules decline where
the linears share a root, decided as a value.

Rubi pocket (2,824 rows of family 1): 2777 -> 2794 solved. The moves re-run
alone gain 19 rows (1.1.1.3 x12, 1.2.1.2:447, 1.2.1.3:1394-1398). Two
sampled rows master answers in 23-24 s timed out under load; at a 60 s
budget both builds answer them with the same allocation to 0.0001%.

Part of #233.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
@Rafael-SOWNet Rafael-SOWNet added this to the 2.6.0 milestone Oct 20, 2026
@Rafael-SOWNet
Rafael-SOWNet merged commit 56caf2c into master Oct 20, 2026
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@github-project-automation github-project-automation Bot moved this from Todo to Done in AngouriMath Oct 20, 2026
Rafael-SOWNet added a commit that referenced this pull request Oct 21, 2026
… x) over its two linears (#1994)

(d + e x)^(7/2)/(b x + c x^2)^2 was answered by a rule late in the chain that
writes the whole integrand as one rational function in t = sqrt(d + e x)
with b e - c d written out, and whose reduction never put its coefficients in
lowest terms: denominators like b^35 c^5 d^31 k^35, one coefficient of
155,000 characters copied into four arms, 937,000 characters in all. The
rule that keeps x (b + c x) for a root above the bar now takes the second
power as well as the third and up: in s = t^2 the integrand is a polynomial
part and partial fractions over s - d and s + rho, rho = (b e - c d)/c,
whose coefficients come from the Taylor series at each root, each linear's
fractions asked as one question, with the atoms d, b e/c, e and P's
coefficients named -- naming whole coefficients hid a cancellation.

Rubi's 1.2.1.2:435 is 2,568 characters from 936,939, and 1.2.1.3:1386 3,933
from 939,897, in about 10 MB from 10-11 GB. Of 83 rows of 1.2.1.2 and
1.2.1.3 with a half-odd power of a linear over a power of b x + c x^2 or
a + b x + c x^2, 20 are shorter and 63 unchanged, character for character,
and no verdict is lost. The #1976 entry's two third-power figures follow.

Part of #233.


Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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