Numerical instability with negative ell

Question

Numerical instability with negative ell

mikeroswell opened this issue 3 years ago · 5 comments

mikeroswell commented 3 years ago

rarity(c(10,1),-1e4) returns Inf, should be about 1.1

Answer 1 · 2022-01-25T00:52:40.000Z

check out Rmpfr https://cran.r-project.org/web/packages/Rmpfr/index.html

Answer 2 · 2022-01-25T03:28:35.000Z

Have you looked at how other Hill-calculating packages handle this?

Answer 3 · 2022-01-25T04:19:08.000Z

Good question. vegan fails sooner with low ell: vegan::renyi(c(10,1), scales =7818, hill=T); returns Inf but MeanRarity::rarity(c(10,1), q= 7818) works, but is better with high ell, where q=-296 fails for MeanRarity::rarity but not vegan::renyi. Need to explore implementation (guessing use of logs and exponents).

Answer 4 · 2022-01-25T16:43:04.000Z

hillR seems to have similar implementation to vegan

Answer 5 · 2022-01-27T14:03:27.000Z

resolved by adding a warning.