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

Calculating dependencies ... done!
Dependency resolution took 1.15 s (backtrack: 0/20).

[ebuild  N     ] virtual/fortran-0-r1::gentoo  USE="openmp" 0 KiB
[ebuild  N     ] virtual/jpeg-100-r1::gentoo  USE="-static-libs" 0 KiB
[ebuild  N     ] sci-libs/openblas-0.3.34::gentoo  USE="openmp -cpudetection -index64 -pthread -relapack -test" 24734 KiB
[ebuild  N     ] sci-libs/lapack-3.12.1-r2::gentoo  USE="deprecated flexiblas lapacke -doc -eselect-ldso -index64 -test" 7879 KiB
[ebuild  N     ] sci-libs/flexiblas-3.5.0::gentoo  USE="openblas openmp system-blas -blis -index64 -mkl -tbb -test" 80741 KiB
[ebuild  N     ] sci-libs/blas-lapack-aux-wrapper-6::gentoo  USE="-index64 -test" 10 KiB
[ebuild  N     ] virtual/cblas-3.8-r1::gentoo  USE="flexiblas -eselect-ldso -index64" 0 KiB
[ebuild  N     ] sci-libs/gsl-2.7.1-r3:0/27::gentoo  USE="cblas-external deprecated -static-libs" 7346 KiB
[ebuild  N     ] media-libs/libpqstego-0.0.1-r2::gentoo  353 KiB
[ebuild  N     ] media-gfx/pqstego-0.0.1::gentoo  153 KiB

Total: 10 packages (10 new), Size of downloads: 121211 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by media-libs/libpqstego-0.0.1-r2::gentoo
# required by media-gfx/pqstego-0.0.1::gentoo
# required by =media-gfx/pqstego-0.0.1 (argument)
>=sci-libs/gsl-2.7.1-r3 cblas-external