---
id: scan-gnu-octave
priority: medium
status: unscanned
created: 2026-03-23
---

## Target

**Repo:** `https://github.com/gnu-octave/octave`
**Language:** C++/m
**Why:** Scientific computing MATLAB-compatible environment — `ismember` in DFS loops in .m graph scripts is O(N) per call; C++ graph code may carry `std::find` on vectors in topological sort.

## Scan command

```bash
# Shallow clone
git clone --depth 1 https://github.com/gnu-octave/octave /tmp/gnu-octave

# Submit to unsandbox
cat > /tmp/scan-gnu-octave.sh << 'EOF'
#!/usr/bin/env bash
set -euo pipefail
GRAPH_KW="tarjan|strongly.connected|dfs|scc|topolog|topo.sort|cycle|reachab|postorder|dominator|liveness|digraph|shortest.path|path.find"
MEM_CPP="std::find|\.count\(|vector.*find|find.*begin.*end|push_back.*visited|visited\.push_back"
MEM_M="ismember|any.*==|find.*==|cellfun.*strcmp"

# C++ sources
find /tmp/gnu-octave/liboctave /tmp/gnu-octave/libinterp -name "*.cc" -o -name "*.h" | sort | while read f; do
  graph_lines=$(grep -inE "$GRAPH_KW" "$f" 2>/dev/null | cut -d: -f1 | head -5 || true)
  [ -z "$graph_lines" ] && continue
  while IFS= read -r lineno; do
    s=$(( lineno > 20 ? lineno - 20 : 1 )); e=$(( lineno + 20 ))
    hit=$(sed -n "${s},${e}p" "$f" 2>/dev/null | grep -iE "$MEM_CPP" | head -1 | sed 's/^\s*//' || true)
    [ -n "$hit" ] && echo "CANDIDATE\t${f}:${lineno}\t${hit}"
  done <<< "$graph_lines"
done

# .m scripts
find /tmp/gnu-octave/scripts -name "*.m" | sort | while read f; do
  graph_lines=$(grep -inE "$GRAPH_KW" "$f" 2>/dev/null | cut -d: -f1 | head -5 || true)
  [ -z "$graph_lines" ] && continue
  while IFS= read -r lineno; do
    s=$(( lineno > 20 ? lineno - 20 : 1 )); e=$(( lineno + 20 ))
    hit=$(sed -n "${s},${e}p" "$f" 2>/dev/null | grep -iE "$MEM_M" | head -1 | sed 's/^\s*//' || true)
    [ -n "$hit" ] && echo "CANDIDATE\t${f}:${lineno}\t${hit}"
  done <<< "$graph_lines"
done
EOF
export UNSANDBOX_PUBLIC_KEY=unsb-pk-russ-test-isth-best
export UNSANDBOX_SECRET_KEY=unsb-sk-rk46c-3zvpg-zjf6z-hjrge
~/git/un-inception/build/un /tmp/scan-gnu-octave.sh
```

## Key files to check

- `scripts/graph/` — Graph algorithm .m scripts (if present); DFS/BFS/SCC implementations
- `scripts/sparse/` — Sparse matrix graph ops; reachability via matrix walk
- `liboctave/util/` — C++ utility data structures; any graph helper with visited tracking
- Any `.m` file containing `tarjan`, `dfs`, or `toposort`

## Expected pattern

Two sub-patterns to look for:
1. In `.m` files: `ismember(node, visited)` inside a DFS while/for loop — `ismember` on a plain array is O(N).
2. In C++ files: `std::find(visited.begin(), visited.end(), v)` where `visited` is a `std::vector` in a topological sort or SCC helper.

## Acceptance criteria

- [ ] Scan run and results saved to `tools/scan-results/gnu-octave.txt`
- [ ] All CANDIDATE hits triaged (confirmed defect or false positive)
- [ ] If confirmed: defect ticket created in `tools/tickets/defects/`