def lu_solve(lu, ipiv, b, trans:"N")
    Lapack.call(:getrs, lu, ipiv, b, trans:trans)[0]
  end
def lu_solve(lu, ipiv, b, trans:"N")
    Lapack.call(:getrs, lu, ipiv, b, trans:trans)[0]
  end
Solves a system of linear equations

     A * X = B  or  A**T * X = B

 with a N-by-N matrix A using the LU factorization computed by
 Numo::Linalg.lu_fact

 @param lu [Numo::NArray] matrix containing the factors L and U
   from the factorization `A = P*L*U` as computed by
   Numo::Linalg.lu_fact.
 @param ipiv [Numo::NArray] The pivot indices from
   Numo::Linalg.lu_fact; for 1<=i<=N, row i of the matrix was
   interchanged with row IPIV(i).
 @param b [Numo::NArray] the right hand side matrix B.
 @param trans [String or Symbol]
   Specifies the form of the system of equations:
     - If 'N': `A * X = B` (No transpose).
     - If 'T': `A*\*T* X = B` (Transpose).
     - If 'C': `A*\*T* X = B` (Conjugate transpose = Transpose).
 @return [Numo::NArray]  the solution matrix X.