Rename lapy[2,3] to sumsq[2,3].
Comments & whitespace
Test Hermitian matrices in unit test nadd-hermitian-matrix.
Unit tests for subtraction of Hermitian matrices.
nsubtract and product for the Hermitian matrix.
Remove npermute, there is no general implementation for this function.

There is not an algorithm for the destructive permutation of a vector or
matrix. This applies to the destructive transpose of a permutation matrix
as well. Since the permutation matrix contains cycles with fixed points,
naive destructive permutation algorithms endlessly repeat and do not
permute rows/columns outside of the first cycle encountered. This is the
same reason that a permutation matrix cannot be destructively tranposed.