ff: Factor form for the given volume
In FI: Provide functions for forest inventory calculations

Description Usage Arguments Value References

This function provide correction for basic volume estimation using cylinder formulation v = DBH^2/4 π H. Factor form is given by taking ratio between real volume and apparent volume.

1	ff(volume, dbh, height)

`volume`	volume of a log, can be the output of `volume`
`dbh`	diameter at breast height (1.3 meters from floor)
`height`	commercial height, length of stem or whatever length of log you used in your estimations of cylinder volume