Hysteresis-Based Conversion (DC/CD Thresholds)

🏷️ Release Title

Hysteresis-Based Conversion (DC/CD Thresholds)

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📝 Release Description

This release introduces a major improvement to the SRCM Engine conversion mechanism by replacing the single-threshold switching rule with a two-threshold hysteresis model.

🚀 Key Changes

🔁 Hysteresis-Based Regime Conversion

• Introduced:

  • DC_threshold — controls discrete → continuous conversion
  • CD_threshold — controls continuous → discrete conversion

• Eliminates rapid oscillations between regimes near threshold boundaries

• Provides more stable and physically realistic hybrid behaviour

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⚙️ Updated Conversion API

• ConversionParams now requires:

  ConversionParams(
      DC_threshold=...,
      CD_threshold=...,
      rate=...,
  )

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🧠 Improved Numerical Stability

• Reduced regime "chattering" in low-density regions
• More robust behaviour in spatially heterogeneous systems
• Better suitability for pattern formation and ecological models

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🧪 Test Suite Updated

• All tests updated to reflect new conversion logic

• Added coverage for:

  • DC/CD masks
  • hysteresis deadband behaviour
  • propensity correctness

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📚 Documentation Updated

• README updated to reflect new conversion model
• Examples now use DC_threshold and CD_threshold
• Clarified behaviour and motivation for hysteresis

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⚠️ Breaking Changes

• Removed:

  ConversionParams(threshold=...)

• All code must now use:

  DC_threshold and CD_threshold

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💡 Why This Matters

The introduction of hysteresis significantly improves the stability of hybrid simulations by preventing frequent switching between discrete and continuous regimes when particle numbers fluctuate near a boundary.

This brings SRCM Engine closer to both:

• physical realism
• numerical robustness