Notation
Three notational conventions are in common use:
- e for the eccentricity and c for the linear eccentricity.
- for the eccentricity and e for the linear eccentricity.
- e or for the eccentricity and f for the linear eccentricity (mnemonic for half-focal separation).
This article makes use of the first notation.
Read more about this topic: Eccentricity (mathematics)