These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.02 s (backtrack: 0/20).

[ebuild  N     ] sci-astronomy/stiff-2.4.0-r1::gentoo  USE="threads -doc" 1049 KiB

Total: 1 package (1 new), Size of downloads: 1049 KiB