We discuss strategies for comparing discrete data points to a catalog (reference) curve by means of the Euclidean distance from each point to the curve in a pump's head H vs. flow Qdiagram. In particular we find that a method currently in use is inaccurate. We propose several alternatives that are accurate, fast, robust and stable.
- orthogonal distance from point to curve
- Schwarz-Christoffel transformation
- cubic splines