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

Calculating dependencies ... done!
Dependency resolution took 0.96 s (backtrack: 0/20).

[ebuild  N     ] sci-mathematics/rngstreams-1.0.1::gentoo  USE="-doc -examples" 491 KiB
[ebuild  N     ] sci-mathematics/unuran-1.8.1::gentoo  USE="rngstreams -doc -examples -gsl -prng" 4307 KiB

Total: 2 packages (2 new), Size of downloads: 4798 KiB