ndarray blas integration for A tranpose dot B

For matrix $A$, calculate

$$ A^TB $$

or

let a = Array2::<f64>::zeros((10000, 1000));
let b = Array2::<f64>::zeros((10000, 1000));
let _ = a.t().dot(&b);

This can be calculated with gemm, however, running the above code doesn't call blas - see src/bin/no-blas.rs.

However, below code does call blas routines, see src/bin/blas.rs.

let b = Array2::<f64>::zeros((10000, 1000));
let at = Array2::<f64>::zeros((1000, 10000));
let _ = at.dot(&b);

Code can be run by

cargo run --profile release --bin blas && cargo run --profile release --bin no-blas

This will generate two profiles in the local directoy, blas.pb and no-blas.pb, which can be view with pprof