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-libs/cln-1.3.7:1::gentoo  USE="-doc -examples" 1306 KiB
[ebuild  N     ] sci-mathematics/ginac-1.8.10::gentoo  USE="-doc -examples" 1483 KiB
[ebuild  N     ] sci-physics/reduze-2.4-r1::gentoo  USE="-berkdb -doc -examples -mpi" 657 KiB

Total: 3 packages (3 new), Size of downloads: 3445 KiB