tubedude / finance-elixir / f6e45358df08bba02533820fb76f00558f4c17ab-PR-24

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Pull #24

github

Scan the bracket interior so even-crossing series find a root

Bracketing compared only the two ends of the rate domain, so a series with
more than one IRR — where both ends share a sign — reported did_not_converge
even though a real rate existed (numpy-financial #39). The bracket now scans
the interior on a geometric grid and returns the sign-change interval nearest
:guess, so a multi-IRR series resolves to the rate a guess-driven spreadsheet
XIRR returns. Both solvers share the bracket. Single-rate series are unchanged.

Ships under 1.6.0 alongside Finance.Solver.Brent.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AVibXT2w1dEdVtMHqffFKn

17 of 17 new or added lines in 3 files covered. (100.0%)

435 of 435 relevant lines covered (100.0%)

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