PHASE3_IMPLEMENTATION_PLAN.md

# Phase 3 Implementation Plan

**Date:** 2026-02-06  
**Status:** In Progress  
**Approach:** Test-Driven Development (TDD)

## Overview

Phase 3 implements proprietary replacements for Array and Matrix Operations in `liboctave/array`. This follows the TDD methodology:
1. Tests are already written ✅
2. Verify tests pass with current implementation (baseline) ✅
3. Implement proprietary replacements with OCTAVE_USE_PHASE3 conditional compilation
4. Verify tests pass with proprietary implementations

## Phase 3 Components

### 3.1 Array Base Classes (Array-base.cc/h)
- **Status**: Implementation exists, marked as "Proprietary implementation"
- **Action**: Add OCTAVE_USE_PHASE3 conditional compilation
- **Files**: `Array-base.cc`, `Array-base.h`

### 3.2 Matrix Operations (dMatrix.cc/h, CMatrix.cc/h, etc.)
- **Status**: Need to verify and add conditional compilation
- **Action**: Review and ensure proprietary implementations
- **Files**: `dMatrix.cc`, `CMatrix.cc`, `fMatrix.cc`, `fCMatrix.cc`

### 3.3 Array Specializations (dNDArray.cc/h, CNDArray.cc/h, etc.)
- **Status**: Need to verify and add conditional compilation
- **Action**: Review and ensure proprietary implementations
- **Files**: `dNDArray.cc`, `CNDArray.cc`, `fNDArray.cc`, `fCNDArray.cc`, etc.

## Implementation Strategy

### Step 1: Verify Baseline ✅
- Run all Phase 3 tests with current implementation
- Document baseline results
- **Status**: test-array-base-complete.cc passes ✅

### Step 2: Add Conditional Compilation
- Add `#if defined (OCTAVE_USE_PHASE3)` guards
- Ensure proprietary code is only compiled when Phase 3 is enabled
- Keep GPL code as fallback when Phase 3 is not enabled

### Step 3: Update Copyright Headers
- When OCTAVE_USE_PHASE3 is defined, use proprietary copyright
- When not defined, keep GPL copyright

### Step 4: Verify Tests Pass
- Run all Phase 3 tests with OCTAVE_USE_PHASE3 enabled
- Ensure all tests pass
- Compare results with baseline

## Build Switch

- **Flag**: `--enable-phase3`
- **Macro**: `OCTAVE_USE_PHASE3`
- **Usage**: `./configure --enable-phase3`

## Test Files

1. `test-array-base-complete.cc` - ✅ Verified working
2. `test-matrix-operations-complete.cc` - ⏳ Needs compilation fixes
3. `test-matrix-decompositions-complete.cc` - ⏳ Needs compilation fixes
4. `test-array-specializations-complete.cc` - ⏳ Needs compilation fixes

## Next Steps

1. ✅ Verify baseline tests
2. ⏳ Add OCTAVE_USE_PHASE3 conditional compilation to Array-base.cc
3. ⏳ Add OCTAVE_USE_PHASE3 conditional compilation to Matrix files
4. ⏳ Add OCTAVE_USE_PHASE3 conditional compilation to Array specialization files
5. ⏳ Fix test compilation issues
6. ⏳ Verify all tests pass with Phase 3 enabled