!-----------------------------------------------------------------
!
! Purpose
! =======
!
! LA_SYSV / LA_HESV computes the solution to a system of linear
! equations
!    A * X = B,
! where A is a symmetric, hermitial or complex matrix and X and B
! are either retriangular matrices or vectors.
! The diagonal pivoting method is used to factor A as
!    A = U * D * U**T,  if UPLO = 'U', or
!    A = L * D * L**T,  if UPLO = 'L',
! where U (or L) is a product of permutation and unit upper (lower)
! triangular matrices, and D is symmetric and block diagonal with
! 1-by-1 and 2-by-2 diagonal blocks.  The factored form of A is then
! used to solve the system of equations A * X = B.
!
! Arguments
! =========
!
!  SUBROUTINE LA_SYSV / LA_HESV( A, B, UPLO, IPIV, INFO )
!    <type>(<wp>), INTENT(INOUT) :: A(:,:), <rhs>
!    CHARACTER(LEN=1), INTENT(IN), OPTIONAL :: UPLO
!    INTEGER, INTENT(OUT), OPTIONAL :: IPIV(:)
!    INTEGER, INTENT(OUT), OPTIONAL :: INFO
!    <type> ::= REAL | COMPLEX
!    <wp>   ::= KIND(1.0) | KIND(1.0D0)
!    <rhs>  ::= B(:,:) | B(:)
!
! =====================
!
! A    (input/output) either REAL or COMPLEX square array,
!      shape (:,:), size(A,1) == size(A,2).
!      On entry, the symmetric matrix A.  If UPLO = 'U', the leading
!      upper triangular part of A contains the upper triangular part
!      of the matrix A, and the strictly lower triangular part of A
!      is not referenced.  If UPLO = 'L', the leading lower triangular
!      part of A contains the lower triangular part of the matrix A,
!      and the strictly upper triangular part of A is not referenced.
!      On exit, if INFO = 0, the block diagonal matrix D and the
!      multipliers used to obtain the factor U or L from the
!      factorization either A = U*D*U**T or A = L*D*L**T.
!
! B    (input/output) either REAL or COMPLEX rectangular array,
!      shape either (:,:) or (:), size(B,1) or size(B) == size(A,1).
!      On entry, the right hand side vector(s) of matrix B for the
!      system of equations AX = B.
!      On exit, if there is no error, the matrix of solution
!      vector(s) X.
!
! UPLO Optional, (input) CHARACTER*1
!      If UPLO is present then:
!         = 'U':  Upper triangle of A is stored;
!         = 'L':  Lower triangle of A is stored.
!      otherwise UPLO = 'U' is assumed.
!
! IPIV Optional (output) INTEGER array, shape (:),
!      size(IPIV) == size(A,1). If IPIV is present it indices that
!      define the permutation matrix P; row i of the matrix was
!      interchanged with row IPIV(i).
!
! INFO Optional (output) INTEGER.
!      If INFO is present
!         = 0: successful exit
!         < 0: if INFO = -k, the k-th argument had an illegal value
!         > 0: if INFO = k, U(k,k) is exactly zero.  The factorization
!              has been completed, but the factor U is exactly
!              singular, so the solution could not be computed.
!      If INFO is not present and an error occurs, then the program is
!         terminated with an error message.
!-------------------------------------

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