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Integrate fractional trigonometric powers two apart by the reduction, and a sine raised from nothing as a derivative - #2031

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Part of #233.

Nineteen of Rubi's trigonometric rows that master f7f2a7a declines or runs out of time on:

  • Fractional powers two apart. A sum of powers of one sine, cosine, secant or cosecant of a linear, with the powers not whole and two apart, by the reduction formula from the highest power down. Each power alone is elliptic, so split, (3 + 3 sec(c + d x)^2)/sqrt(sec(c + d x)) was two declined integrals. Beside x, by parts once.
  • A sine raised from nothing. The derivative of a sine times powers of the cosine and sums in it, or of a cosine beside the sine: (a + a cos(x))^(3/2)/cos(x)^(5/4).
  • An irrational power of the sine. A cosine beside a function of the sine with a power of it that is not rational, in s = sin(x): cos(x)/(sin(x) + sin(x)^sqrt(2)).
  • A root of a power. (c sin(a + b x)^n)^(1/n) as a constant times sin(a + b x) between the zeros of the sine, and the same for the cosine.
  • Three repairs inside existing substitutions. Factors written alike on both sides of the bar are cancelled under the homogeneous substitution, a whole power of a product is distributed under the tangent, and sqrt(1 - cos(x)^2) beside a root of 1 - cos(x) is written as the product of the roots of 1 - cos(x) and 1 + cos(x).

Chain against master f7f2a7a:

  • The pocket of 2,005 rows went from 1,979 to 1,998 solved, with 0 wrong.
  • Family 4's sample went from 1,025 to 1,026; the other samples are unchanged.
  • The 19 rows that moved, run alone, went from 0 to 19 solved.
  • 7,510 rows were compared for allocation, and none grew by more than 55 MB.

The full unit suite passes locally. The one failure it had was this branch's own new test, which pinned c > 0 in the answer to (c x^n)^(1/n). Since #2012, master writes that as x (c x^n)^(1/n)/2, which is right on every branch, and the test now pins that. The BREAKING-CHANGES lengths were re-measured on this branch: five had moved with the rebase. The v2.5.0 column was measured on a v2.5.0 build.

This overlaps with #2026 on sqrt(1 - cos(x))/sqrt(a - cos(x)): both answer it. Whichever merges second gets its entry re-measured.

🤖 Generated with Claude Code

https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

… and a sine raised from nothing as a derivative

- A sum of powers of one sine, cosine, secant or cosecant of a linear, the
  powers not whole and two apart, by the reduction formula from the highest
  down; each power alone is elliptic. Beside x, by parts once.
- The derivative of a sine raised from nothing times powers of the cosine
  and sums in it, or of a cosine beside the sine.
- A cosine beside a function of the sine with a power of it that is not
  rational, in s = sin(x).
- (c sin(a + b x)^n)^(1/n) as a constant times sin(a + b x) between the
  zeros of the sine, and so for the cosine.
- Under the homogeneous substitution, factors written alike on both sides
  cancelled; under the tangent, a whole power of a product distributed; and
  the root of 1 - cos(x)^2 beside a root of 1 - cos(x) as the product of
  the roots of 1 - cos(x) and 1 + cos(x).

Chain against master f7f2a7a: pocket of 2,005 rows, 1,979 -> 1,998 solved,
0 wrong; family 4's sample 1,025 -> 1,026, the others unchanged; the 19 rows that
moved, alone, 0 -> 19 solved; 7,510 rows compared for allocation, none grew
past 55 MB.

The new test that the power-of-x case is left to the rules before it pinned
`c > 0` in the answer to (c x^n)^(1/n), as those wrote it before #2012; master
writes x (c x^n)^(1/n)/2, whose derivative is the integrand on every branch
since d/dx (c x^n)^(1/n) = (c x^n)^(1/n)/x, and the test pins that.

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 21, 2026
@Rafael-SOWNet
Rafael-SOWNet merged commit fc1d521 into master Oct 21, 2026
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@github-project-automation github-project-automation Bot moved this from Todo to Done in AngouriMath Oct 21, 2026
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