| brink | Small taper dataset from Brink and von Gadow (1986). |
| decay | Decay function delta |
| hlevel | Height level for given diameter or area. |
| Id | Integral of decay function. |
| Idd | Double integral of decay function. |
| taper | Tree taper (or profile) equation. |
| tbase | Unscaled base taper curve of cross-sectional area vs height level. |
| volume | Volume between two height levels. |