SUBROUTINE CPBSV_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 => SP USE LA_AUXMOD, ONLY: ERINFO, LSAME USE F77_LAPACK, ONLY: PBSV_F77 => LA_PBSV ! .. IMPLICIT STATEMENT .. IMPLICIT NONE ! .. SCALAR ARGUMENTS .. CHARACTER(LEN=1), INTENT(IN), OPTIONAL :: UPLO INTEGER, INTENT(OUT), OPTIONAL :: INFO ! .. ARRAY ARGUMENTS .. COMPLEX(WP), INTENT(INOUT) :: A(:,:), B(:,:) !---------------------------------------------------------------------- ! ! Purpose ! ======= ! ! LA_PBSV computes the solution to a linear system of equations ! A*X = B, where A has band form and 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 band matrix and L is a lower triangular ! band matrix, each with the same number of superdiagonals or subdiagonals ! as A. The factored form of A is then used to solve the above system. ! ! ========= ! ! SUBROUTINE LA_PBSV( AB, B, UPLO=uplo, INFO=info ) ! (), INTENT(INOUT) :: AB(:,:), ! CHARACTER(LEN=1), INTENT(IN), OPTIONAL :: UPLO ! INTEGER, INTENT(OUT), OPTIONAL :: INFO ! where ! ::= REAL | COMPLEX ! ::= KIND(1.0) | KIND(1.0D0) ! ::= B(:,:) | B(:) ! ! Arguments ! ========= ! ! AB (input/output) REAL or COMPLEX array, shape (:,:) with ! size(AB,1) = kd + 1 and size(AB,2) = n, where kd is the number ! of superdiagonals or subdiagonals in the band and n is the ! order of A. ! On entry, the upper (if UPLO = 'U') or lower (if UPLO = 'L') ! triangle of matrix A in band storage. The (kd + 1) diagonals of ! A are stored in the rows of AB so that the j-th column of A is ! stored in the j-th column of AB as follows: ! if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j ! 1<=j<=n ! if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd) ! 1<=j<=n. ! On exit, the factor U or L from the Cholesky factorization ! A = U^H*U = L*L^H in the same storage format as A. ! B (input/output) REAL or COMPLEX array, shape (:,:) with ! size(B,1) = n or shape (:) with size(B) = n. ! 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: successful 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_PBSV' ! .. LOCAL SCALARS .. CHARACTER(LEN=1) :: LUPLO INTEGER :: LINFO, KD, N, NRHS ! .. INTRINSIC FUNCTIONS .. INTRINSIC SIZE, PRESENT ! .. EXECUTABLE STATEMENTS .. LINFO = 0; KD = SIZE(A,1)-1; N = SIZE(A,2); NRHS = SIZE(B,2) IF( PRESENT(UPLO) ) THEN; LUPLO = UPLO; ELSE; LUPLO = 'U'; ENDIF ! .. TEST THE ARGUMENTS IF( KD < 0 .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 PBSV_F77( LUPLO, N, KD, NRHS, A, KD+1, B, N, LINFO ) END IF CALL ERINFO( LINFO, SRNAME, INFO ) END SUBROUTINE CPBSV_F95