SUBROUTINE DSYSV( UPLO, N, NRHS, A, LDA, IPIV, B, LDB, WORK, LWORK, * INFO) CHARACTER * 1 UPLO INTEGER N, NRHS, LDA, LDB, LWORK, INFO INTEGER IPIV(*) DOUBLE PRECISION A(LDA,*), B(LDB,*), WORK(*) SUBROUTINE DSYSV_64( UPLO, N, NRHS, A, LDA, IPIV, B, LDB, WORK, * LWORK, INFO) CHARACTER * 1 UPLO INTEGER*8 N, NRHS, LDA, LDB, LWORK, INFO INTEGER*8 IPIV(*) DOUBLE PRECISION A(LDA,*), B(LDB,*), WORK(*)
SUBROUTINE SYSV( UPLO, N, NRHS, A, [LDA], IPIV, B, [LDB], [WORK], * [LWORK], [INFO]) CHARACTER(LEN=1) :: UPLO INTEGER :: N, NRHS, LDA, LDB, LWORK, INFO INTEGER, DIMENSION(:) :: IPIV REAL(8), DIMENSION(:) :: WORK REAL(8), DIMENSION(:,:) :: A, B SUBROUTINE SYSV_64( UPLO, N, NRHS, A, [LDA], IPIV, B, [LDB], [WORK], * [LWORK], [INFO]) CHARACTER(LEN=1) :: UPLO INTEGER(8) :: N, NRHS, LDA, LDB, LWORK, INFO INTEGER(8), DIMENSION(:) :: IPIV REAL(8), DIMENSION(:) :: WORK REAL(8), DIMENSION(:,:) :: A, B
void dsysv(char uplo, int n, int nrhs, double *a, int lda, int *ipiv, double *b, int ldb, int *info);
void dsysv_64(char uplo, long n, long nrhs, double *a, long lda, long *ipiv, double *b, long ldb, long *info);
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.
On exit, if INFO = 0, the block diagonal matrix D and the multipliers used to obtain the factor U or L from the factorization A = U*D*U**T or A = L*D*L**T as computed by SSYTRF.
If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.