SUBROUTINE DSYEVD( JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, IWORK, * LIWORK, INFO) CHARACTER * 1 JOBZ, UPLO INTEGER N, LDA, LWORK, LIWORK, INFO INTEGER IWORK(*) DOUBLE PRECISION A(LDA,*), W(*), WORK(*) SUBROUTINE DSYEVD_64( JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, IWORK, * LIWORK, INFO) CHARACTER * 1 JOBZ, UPLO INTEGER*8 N, LDA, LWORK, LIWORK, INFO INTEGER*8 IWORK(*) DOUBLE PRECISION A(LDA,*), W(*), WORK(*)
SUBROUTINE SYEVD( JOBZ, UPLO, N, A, [LDA], W, [WORK], [LWORK], * [IWORK], [LIWORK], [INFO]) CHARACTER(LEN=1) :: JOBZ, UPLO INTEGER :: N, LDA, LWORK, LIWORK, INFO INTEGER, DIMENSION(:) :: IWORK REAL(8), DIMENSION(:) :: W, WORK REAL(8), DIMENSION(:,:) :: A SUBROUTINE SYEVD_64( JOBZ, UPLO, N, A, [LDA], W, [WORK], [LWORK], * [IWORK], [LIWORK], [INFO]) CHARACTER(LEN=1) :: JOBZ, UPLO INTEGER(8) :: N, LDA, LWORK, LIWORK, INFO INTEGER(8), DIMENSION(:) :: IWORK REAL(8), DIMENSION(:) :: W, WORK REAL(8), DIMENSION(:,:) :: A
void dsyevd(char jobz, char uplo, int n, double *a, int lda, double *w, int *info);
void dsyevd_64(char jobz, char uplo, long n, double *a, long lda, double *w, long *info);
The divide and conquer algorithm makes very mild assumptions about floating point arithmetic. It will work on machines with a guard digit in add/subtract, or on those binary machines without guard digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2. It could conceivably fail on hexadecimal or decimal machines without guard digits, but we know of none.
Because of large use of BLAS of level 3, SSYEVD needs N**2 more workspace than SSYEVX.
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.
If LIWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the IWORK array, returns this value as the first entry of the IWORK array, and no error message related to LIWORK is issued by XERBLA.