SUBROUTINE DPOSV_F95( A, B, UPLO, INFO ) ! ! -- LAPACK95 interface driver routine (version 3.0) -- ! UNI-C, Denmark; Univ. of Tennessee, USA; NAG Ltd., UK ! September, 2000 ! ! .. USE STATEMENTS .. USE LA_PRECISION, ONLY: WP => DP USE LA_AUXMOD, ONLY: ERINFO, LSAME USE F77_LAPACK, ONLY: POSV_F77 => LA_POSV ! .. IMPLICIT STATEMENT .. IMPLICIT NONE ! .. SCALAR ARGUMENTS .. CHARACTER(LEN=1), INTENT(IN), OPTIONAL :: UPLO INTEGER, INTENT(OUT), OPTIONAL :: INFO ! .. ARRAY ARGUMENTS .. REAL(WP), INTENT(INOUT) :: A(:,:), B(:,:) !---------------------------------------------------------------------- ! ! Purpose ! ======= ! ! LA_POSV computes the solution to a linear system of equations ! A*X=B, where A is real symmetric or complex Hermitian and, in either ! case, positive definite, and where X and B are rectangular matrices ! or vectors. The Cholesky decomposition is used to factor A as ! A = U^H*U if UPLO = 'U', or A = L*L^H if UPLO = 'L' ! where U is an upper triangular matrix and L is a lower triangular ! matrix (L = U^H ). The factored form of A is then used to solve the ! above system. ! ! ========= ! ! SUBROUTINE LA_POSV( A, B, UPLO=uplo, INFO=info ) ! (), INTENT(INOUT) :: A(:,:), ! CHARACTER(LEN=1), INTENT(IN), OPTIONAL :: UPLO ! INTEGER, INTENT(OUT), OPTIONAL :: INFO ! where ! ::= REAL | COMPLEX ! ::= KIND(1.0) | KIND(1.0D0) ! ::= B(:,:) | B(:) ! ! Arguments ! ========= ! ! A (input/output) REAL or COMPLEX square array, shape (:,:). ! On entry, the matrix A. ! If UPLO = 'U', the 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 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, the factor U or L from the Cholesky factorization ! A = U^H*U = L*L^H. ! B (input/output) REAL or COMPLEX array, shape (:,:) with ! size(B,1) = size(A,1) or shape (:) with size(B) = size(A,1). ! On entry, the matrix B. ! On exit, the solution matrix X. ! UPLO Optional (input) CHARACTER(LEN=1) ! = 'U': Upper triangle of A is stored; ! = 'L': Lower triangle of A is stored. ! Default value: 'U'. ! INFO Optional (output) INTEGER ! = 0: sauccessful exit. ! < 0: if INFO = -i, the i-th argument had an illegal value. ! > 0: if INFO = i, the leading minor of order i of A is not ! positive definite, so the factorization could not be ! completed and the solution could not be computed. ! If INFO is not present and an error occurs, then the program is ! terminated with an error message. !---------------------------------------------------------------------- ! .. PARAMETERS .. CHARACTER(LEN=7), PARAMETER :: SRNAME = 'LA_POSV' ! .. LOCAL SCALARS .. CHARACTER(LEN=1) :: LUPLO INTEGER :: LINFO, N, NRHS ! .. INTRINSIC FUNCTIONS .. INTRINSIC SIZE, PRESENT ! .. EXECUTABLE STATEMENTS .. LINFO = 0; N = SIZE(A,1); NRHS = SIZE(B,2) IF( PRESENT(UPLO) )THEN; LUPLO = UPLO; ELSE; LUPLO = 'U'; END IF ! .. TEST THE ARGUMENTS IF( SIZE( A, 2 ) /= N .OR. N < 0 ) THEN; LINFO = -1 ELSE IF( SIZE( B, 1 ) /= N .OR. NRHS < 0 ) THEN; LINFO = -2 ELSE IF( .NOT.LSAME(LUPLO,'U') .AND. .NOT.LSAME(LUPLO,'L') )THEN; LINFO = -3 ELSE IF ( N > 0 ) THEN CALL POSV_F77( LUPLO, N, NRHS, A, N, B, N, LINFO ) END IF CALL ERINFO( LINFO, SRNAME, INFO ) END SUBROUTINE DPOSV_F95