Implement exact summation (fsum)?
Fil opened this issue · 1 comments
Fil commented
Discussed with Kahan summation (#33, #149), fsum is a bit slower but provably "exact" and would be the preferred "exact summation" algorithm for d3-array.
I've implemented it in https://observablehq.com/d/723090bd2ef54f5f ; it does not return a sum but an object that can be used to continue the sum by adding more terms.
- speed test (about 2x slower than d3.sum which is not that bad)
- a valueof accessor
- check if this implementation is useful in d3-geo.
- document
Fil commented
Good news: replacing d3-geo/adder with fsum can help solve https://observablehq.com/@fil/small-circle-test by enhancing the precision of the sums.