Function lnSign

src/compute-engine/library/arithmetic.ts:201–209

Determines sgn of ln(x)

(x: Expression)

/** The tier of a real quotient whose divisor may be zero: a finite real,
 * the projective `~oo` of `1/0`, or the `NaN` of `0/0` — never a non-real
 * finite complex, so this is strictly tighter than `number` (lattice
 * ruling L3: over-admit only within the `infinity` branch). */
// Built as a literal node, not `parseType(...)`: this runs at module
// initialization, and under jest's CommonJS module graph `parse.js` is not
// yet initialized when this file's top level executes (a temporal-dead-zone
// `ReferenceError`); `tsx` happened to order the modules differently.
// Frozen: returned BY REFERENCE from the Divide and Power handlers and
// stored as-is (the parse fast path and the widening walker both return a
// valid, unchanged node by identity), so an in-place mutation anywhere
// downstream would corrupt every later pole type in the process — the
// same rationale as `EXTENDED_REAL_TYPE` in `common/type/primitive.ts`.