documentation for xtensor-blas

 xtensor-blas is an extension to the header-only xtensor library,
 offering bindings to BLAS and LAPACK libraries through cxxblas and
 cxxlapack from the FLENS project.
 .
 xtensor-blas currently provides non-broadcasting dot, norm (1- and
 2-norm for vectors), inverse, solve, eig, cross, det, slogdet,
 matrix_rank, inv, cholesky, qr, svd in the xt::linalg namespace
 (check the corresponding xlinalg.hpp header for the function
 signatures). The functions, and signatures, are trying to be 1-to-1
 equivalent to NumPy. Low-level functions to interface with BLAS or
 LAPACK with xtensor containers are also offered in the blas and
 lapack namespace.
 .
 This package provides documentation for xtensor-blas.