rajamesandClaude Opus 5.5
a2d21d5cda
D-12 (ruled 2026-10-02): Q.SQRT of a negative value and Q.LOG of zero or a negative value return 0 and set NODE-ERROR, as Q./ does on division by zero. Q.SQRT is v3's q48_sqrt_approx: Newton from x0 = q/2 + 0.25, up to 8 rounds of x' = (x + q/x) / 2, returning x once |x' - x| < 10 ulp; sqrt(0) = 0 and sqrt(1.0) = 1.0. q, x and the rounds left live in a 5-cell variable (QR). Checked bit for bit against v3's q48_sqrt_approx (ported into the test) on 19 edge values and 3000 pseudo-random q below 2^48, at both cell widths, optimised and ASan+UBSan. Above 2^48 v3's q48_div saturates and v4 divides correctly, so there is no parity there. Bug found and fixed on the way: the "< 10 ulp" test subtracted 10 from the step's low cell as a signed number, so at 32-bit cells a step of 2^31 or more read as small and the iteration stopped early. It now tests the low cell's top bit first, as Q.EXP does. The first test run missed it because `make build/32-test_foundation.c` rebuilds nothing (the Makefile's rules use absolute paths); the mutation runs, compiled from source, exposed it. Only `make test` is used from here. Headroom (data under arg / return): Q.SQRT 3/2. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
v4/
StarForth v4: the 32-instruction F18-derived core. The design lives in
docs/v4.0.0/JUSTIFICATION.md (why) and docs/v4.0.0/DECOMPOSITION.md
(every v3 word mapped to a v4 fate).
The first deliverable is the hosted C99 golden model (JUSTIFICATION.md §10,
step 1). It must pass POST and hold K≡1.0 with 32- and 64-bit cells on all
three host ISAs.
What exists so far is the single node: registers, circular stacks, memory, all
32 opcodes, and per-opcode and per-call-target heat. make -C v4 test builds
and runs the tests at both cell widths; make -C v4 sanitize repeats them
under ASan and UBSan. There is no compiler capsule, no POST and no K
measurement yet.