Function sparse_eigs 

pub fn sparse_eigs<F>(
    matrix: &CsrMatrix<F>,
    n_eigenvalues: usize,
    target: EigenvalueTarget,
    tol: Option<f64>,
) -> SparseResult<SparseEigenResult<F>>
where
    F: Float + NumAssign + Sum + SparseElement + Debug + 'static,

Convenience function: compute eigenvalues of a general (possibly non-symmetric) matrix.