11 refactor model analysis

[rdesarz]

This changelog summarizes the work developed on branch 11-refactor-model-analysis.

Added

• Checked model constructors with typed errors:
  • ContinuousStateSpaceModel::try_from_matrices(...)
  • DiscreteStateSpaceModel::try_from_matrices(...)
  • ModelError (MatrixANotSquare, DimensionMismatch, InvalidSamplingDt, SingularMatrix)
• Consolidated LTI analysis API:
  • analysis::analyze_lti(...)
  • TimeDomain (Continuous, Discrete)
  • LtiAnalysisReport (poles, spectral radius, stability, controllability/observability diagnostics)
• Expanded simulator API and tests:
  • Generic simulate(...)
  • Step, impulse, and ramp response validation with nominal-value tests
  • Error-path tests for invalid dimensions/duration/sampling time
• New analysis-first example:
  • examples/analysis_report.rs

Changed

• Discretization strategy simplified and refocused for control-library coherence:
  • Exposed discretization narrowed to ZOH only
• Simulation behavior uses full output equation consistently:
  • y = Cx + Du
• Documentation improvements:
  • Expanded Rustdoc in model.rs with equations and assumptions
  • Detailed comments on matrix exponential algorithm, including references
  • Added explanatory comments for all unit tests
  • Added top-of-file purpose comments in examples
• CI workflow hardening:
  • Reliable fontconfig install in GitHub Actions (apt-get update + libfontconfig1-dev)

Removed

• Controller implementation from this branch scope (deferred to future work)
• LQR implementation/example behavior (placeholder kept for future controller work)
• simulate_with_noise(...) (kept simulator scope deterministic)
• Non-target discretization methods from public API:
  • Forward Euler
  • Backward Euler
  • Tustin

Breaking Changes

• Legacy/unsafe model constructors were deprecated or removed in favor of checked constructors.
• Controller APIs introduced earlier in the branch were removed before final scope stabilization.
• Discretization API reduced to ZOH to keep the public surface minimal.

Quality / Verification

• Unit test suite expanded substantially for analysis and simulation behavior.
• Edge/error cases now covered explicitly (dimension mismatch, invalid duration, invalid dt).
• Current branch state passes:
  • cargo test (unit tests + doctests)

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[chatgpt-codex-connector]

Remove non-existent controller APIs from README highlights

The README now advertises controller helpers (pole placement/LQR/closed-loop assembly), but this commit’s public API only exposes analysis, model, simulator, and trajectory modules (src/lib.rs), so users relying on these bullets will look for APIs that are not present and hit compile-time failures when trying to adopt the library from documentation alone. Please align the highlights with what this revision actually ships.

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