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Integrate an exponential of a quadratic over the linear through its vertex - #1951

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an-exponential-of-a-quadratic-over-the-linear-through-its-vertex
Oct 19, 2026
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Part of #233.

f^(a + b x + c x^2)/(b + 2 c x)^n was declined. Under u = b + 2 c x the exponent is u^2/(4 c) + a - b^2/(4 c), with no linear part, and the integrand is a moment about 0 of the Gaussian, which the integrator answers. An odd n gives the exponential integral of the square, and an even one the error function. The new rule, SolveAnExponentialOfAQuadraticOverTheLinearThroughItsVertex, takes only a linear whose root is the vertex (2 A p = q B, decided as a value). Elsewhere the shift leaves a linear part: e^(x^2 + 2 x)/(x + 2) is still declined, and is pinned by a test.

Measured against master 8a1ef454:

master this branch
Rubi family 2, all 650 rows 604 610 (2.3: 510-512, 516-518)
moves, each re-run alone 6 unevaluated → solved, 0 wrong (a seventh, 3.5:37, is a timing artefact that master also solves alone)
families 0 (whole) and 1 (40 a file), samples of 2–8 identical
performance gate passed
suite 15,602 passed, 0 failed

Rebased onto #1950 without conflict. Both together put family 2 at 635 of 650. All six rows were declined by 2.5.0 too, and BREAKING-CHANGES.md has the entry.

🤖 Generated with Claude Code

https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

…ertex

f^(a + b x + c x^2)/(b + 2 c x)^n was declined. Under u = b + 2 c x the
exponent is u^2/(4 c) + a - b^2/(4 c), with no linear part, and the integrand
is a moment about 0 of the Gaussian, which the integrator answers: the
exponential integral of the square for an odd n, the error function for an
even one. The exponent in u is written from the coefficients, and the
vertex condition 2 A p = q B is decided as a value.

Rubi's 2.3: 6 rows go from unevaluated to solved, 0 wrong. Families 0 and 1
and samples of 2-8 otherwise identical; gate and suite pass.

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 19, 2026
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Rafael-SOWNet merged commit 0f0ff07 into master Oct 19, 2026
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@github-project-automation github-project-automation Bot moved this from Todo to Done in AngouriMath Oct 19, 2026
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Rafael-SOWNet deleted the an-exponential-of-a-quadratic-over-the-linear-through-its-vertex branch October 29, 2026 00:43
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