Roadmap

go-ruby-matrix/matrix is grown test-first, each capability differential-tested against MRI rather than built in isolation. Ruby's matrix standard library — the deterministic, interpreter-independent slice — is complete.

Stage	What	Status
The Num numeric tower	Entries flow through Num (*big.Int Integers, *big.Rat Rationals, float64 Floats) with Ruby's promotion: Integer op Integer stays Integer, any Rational stays Rational even when whole, any Float dominates.	Done
Constructors & accessors	New / Build / Identity / Zero / Diagonal / Scalar / RowVector / ColumnVector / Rows / Columns / HStack / VStack; RowCount / ColumnCount / At / Row / Column / Each / Minor / FirstMinor / ToA.	Done
Exact operations	Add / Sub / Neg / Mul (matrix·matrix, ·scalar, ·vector) / Div / Pow / Transpose / Trace / Determinant / Inverse / Rank — exact over the tower, reproducing MRI's inverse_from Gauss-Jordan step for step.	Done
Predicates & formatting	Square / IsDiagonal / Symmetric / Orthogonal / Singular / Regular / LowerTriangular / UpperTriangular / IsZero; Eql (==), Hash; ToS / Inspect (Matrix[[…], […]], Matrix.empty(r, c)).	Done
Vector	Elements / At / Size / Add / Sub / Mul / InnerProduct (dot) / CrossProduct / Magnitude (norm) / Normalize / Each / Map / Angle / Eql / Independent.	Done
Differential oracle & coverage	Deterministic ruby-free tests hold coverage at 100%; a differential oracle compares every operation's ToS against ruby -rmatrix … .inspect, including the exact-arithmetic results and the Ruby-faithful float formatter; gofmt + go vet clean, green across all six 64-bit Go arches and three OSes.	Done

Documented out-of-scope boundaries

These are deliberate, recorded so the module's surface is unambiguous:

• No interpreter. The library implements the deterministic arithmetic; it never runs arbitrary Ruby. Mapping a host's live numerics to and from the Num tower is the consumer's job — that is why rbgo binds this module rather than the reverse.
• Reference is reference Ruby (MRI). Byte-for-byte conformance targets MRI 4.0.5's matrix; the differential oracle gates on RUBY_VERSION >= "4.0".
• Standalone & reusable. The module has no dependency on the Ruby runtime; the dependency runs the other way.

See Usage & API for the surface and Why pure Go for the deterministic/interpreter split.