| # Convex Hull of Floating-Point Points | |
| ## Description | |
| Given planar points with finite floating-point coordinates, compute their convex hull using Andrew's monotone-chain algorithm. | |
| ## Input | |
| The verification-case input consists of an array `pts` of `n` points and writable output array `hull`. | |
| ## Output | |
| The function produces the number of hull points, with the hull written to `hull` in boundary order. | |
| ## Constraints | |
| - $0 \le n \le 50000$ and every arithmetic result required by the comparisons is finite. | |
| ## Source | |
| Classical algorithmic problem reconstructed from the verified C artifact. | |