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Write whole powers of a root as powers of its radicand before measuring where it holds - #2046
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Rafael-SOWNet merged 1 commit intoOct 22, 2026
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…ng where it holds Rubi's 1.1.3.2 1/(x^(7/2) sqrt(a + b x^5)), three like it, and 1.3.2's sqrt(a x^23)/sqrt(1 + x^5) and sqrt(a x^13)/sqrt(1 + x^5) were answered provided x >= 0. The integrand is real beyond -(a/b)^(1/5) as a product of two imaginary roots, and the answer holds there, but it spelled x^5 as ((x^(1/2))^5)^2: real at a negative x with a zero imaginary part, the outer root on its cut, which the interval and decimal evaluations rightly refuse, so WhereTheDerivativeHoldsBeyondTheRadicand could not read the answer there and the condition stayed. Under u = B^(1/q), a whole power of u that is a multiple of q is now written as the power of B it is on every branch, (B^(1/q))^(k q) = B^k, nested whole powers flattened first, both in that substitution's answer and in ConditionedOnTheRadicand, which every root substitution's condition passes through: the measurement then shows the answer holds everywhere, and the condition is not written. 1.1.1.2's 1/(sqrt(x) sqrt(2 x - 3)) had (x^(1/2))^2 on the same cut by another route. Part of #233. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
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Part of #233.
u = sqrt(x), Rubi's 1.1.3.21/(x^(7/2) sqrt(a + b x^5))came back withx^5spelled((x^(1/2))^5)^2, underprovided x >= 0. The same happened to three like it, to 1.3.2'ssqrt(a x^23)/sqrt(1 + x^5)andsqrt(a x^13)/sqrt(1 + x^5), and to 1.1.1.2's1/(sqrt(x) sqrt(2 x - 3)).-(a/b)^(1/5), as a product of two imaginary roots, and the answer holds there. ButWhereTheDerivativeHoldsBeyondTheRadicandevaluates((x^(1/2))^5)^2at a negative x with a zero imaginary part, on the outer root's cut, and could not say so.WithWholePowersOfARootAsPowersOfItsRadicandflattens a whole power of a root and folds(B^(1/q))^n, where q divides n, intoB^(n/q), which holds on every branch. It is applied to the substitution's back-substituted answer and at the start ofConditionedOnTheRadicand. The condition is gone, and the answers are shorter.1/(x^(7/2) sqrt(a + b x^5))1/(x^(17/2) sqrt(a + b x^5))1/(x^(7/2) sqrt(1 + x^5))1/(x^(17/2) sqrt(1 + x^5))sqrt(a x^23)/sqrt(1 + x^5)sqrt(a x^13)/sqrt(1 + x^5)1/(sqrt(x) sqrt(2 x - 3))"For x >= 0 only" is the probe at -2.3 and -1.7: the answer has no value at 2 of 5 points where the integrand has one.
Chain against master 78cd31b:
The full unit suite ran locally with 16,552 passed and 1 failed. The failure was
IntegralAnswerCacheTest.AnIntegralWithNoAnswerStillFinishesQuicklyat a load of 17, and it passes alone in 2 s. The BREAKING-CHANGES lengths were measured on the branch. Rebased onto ef4150e.🤖 Generated with Claude Code
https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura