# Specs Index
This index lists every spec in `docs/specs/`, ordered from foundational decisions to the
ones that build on them. Read top to bottom for the full picture; jump directly to a spec
if you already know the area you're touching.
## Crate shape and layering
The decisions everything else sits on top of: how the crate is distributed, how it's
layered internally, and what the core scalar and storage abstractions look like.
- [Single Crate with Incremental Feature Flags](single-crate-feature-flags.md)
- [Trait-Based Generic Layered Architecture](layered-generic-architecture.md)
- [Generic Scalar Type](generic-scalar-type.md)
- [Hybrid Memory Allocation Strategy](hybrid-memory-allocation.md)
- [Minimal Shared Storage Trait Between Static and Dynamic Types](static-dynamic-storage-trait.md)
## Cross-cutting conventions
Conventions that apply across every module, independent of which mathematical domain
they show up in.
- [Per-Module Error Handling with Result](per-module-error-handling.md)
- [NaN/Inf Policy](nan-inf-policy.md)
## Scalar functions and numerical tolerance
How elementary functions are implemented and how the library decides when a computed
value is small enough to treat as zero.
- [Public Elementary Scalar Functions, Scoped to Internal Needs](elementary-scalar-functions.md)
- [Elementary Function Precision](elementary-function-precision.md)
- [Numerical Tolerance for Approximate-Zero Comparisons](approximate-zero-tolerance.md)
- [Auto-Computed Tolerance Defaults](auto-tolerance-defaults.md)
## Dense matrix API
- [Two-Level Public API for Matrix Operations](two-level-matrix-api.md)
## Sparse matrix API
Sparse-specific decisions, ordered from the underlying storage representation up to the
operations built on it.
- [Sparse Index Type (u32)](sparse-index-type.md)
- [Sparse Matrix Public API Shape](sparse-matrix-api-shape.md)
- [SortedCsrMatrix — Type-Level Column-Sort Invariant](sorted-csr-matrix.md)
- [Sparse Entry Pruning and Explicit Zero Semantics](sparse-entry-pruning.md)
## Krylov subspace methods
- [Krylov Basis-Size Const-Generic Convention](krylov-basis-size-const-generics.md)
- [Krylov Tolerance and Convergence Criteria](krylov-tolerance-and-convergence.md)