zsteqr - compute all eigenvalues and, optionally, eigenvectors of a symmetric tridiagonal matrix using the implicit QL or QR method
SUBROUTINE ZSTEQR(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER*1 COMPZ DOUBLE COMPLEX Z(LDZ,*) INTEGER N, LDZ, INFO DOUBLE PRECISION D(*), E(*), WORK(*) SUBROUTINE ZSTEQR_64(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER*1 COMPZ DOUBLE COMPLEX Z(LDZ,*) INTEGER*8 N, LDZ, INFO DOUBLE PRECISION D(*), E(*), WORK(*) F95 INTERFACE SUBROUTINE STEQR(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER(LEN=1) :: COMPZ COMPLEX(8), DIMENSION(:,:) :: Z INTEGER :: N, LDZ, INFO REAL(8), DIMENSION(:) :: D, E, WORK SUBROUTINE STEQR_64(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER(LEN=1) :: COMPZ COMPLEX(8), DIMENSION(:,:) :: Z INTEGER(8) :: N, LDZ, INFO REAL(8), DIMENSION(:) :: D, E, WORK C INTERFACE #include <sunperf.h> void zsteqr(char compz, int n, double *d, double *e, doublecomplex *z, int ldz, int *info); void zsteqr_64(char compz, long n, double *d, double *e, doublecomplex *z, long ldz, long *info);
Oracle Solaris Studio Performance Library zsteqr(3P) NAME zsteqr - compute all eigenvalues and, optionally, eigenvectors of a symmetric tridiagonal matrix using the implicit QL or QR method SYNOPSIS SUBROUTINE ZSTEQR(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER*1 COMPZ DOUBLE COMPLEX Z(LDZ,*) INTEGER N, LDZ, INFO DOUBLE PRECISION D(*), E(*), WORK(*) SUBROUTINE ZSTEQR_64(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER*1 COMPZ DOUBLE COMPLEX Z(LDZ,*) INTEGER*8 N, LDZ, INFO DOUBLE PRECISION D(*), E(*), WORK(*) F95 INTERFACE SUBROUTINE STEQR(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER(LEN=1) :: COMPZ COMPLEX(8), DIMENSION(:,:) :: Z INTEGER :: N, LDZ, INFO REAL(8), DIMENSION(:) :: D, E, WORK SUBROUTINE STEQR_64(COMPZ, N, D, E, Z, LDZ, WORK, INFO) CHARACTER(LEN=1) :: COMPZ COMPLEX(8), DIMENSION(:,:) :: Z INTEGER(8) :: N, LDZ, INFO REAL(8), DIMENSION(:) :: D, E, WORK C INTERFACE #include <sunperf.h> void zsteqr(char compz, int n, double *d, double *e, doublecomplex *z, int ldz, int *info); void zsteqr_64(char compz, long n, double *d, double *e, doublecomplex *z, long ldz, long *info); PURPOSE zsteqr computes all eigenvalues and, optionally, eigenvectors of a sym- metric tridiagonal matrix using the implicit QL or QR method. The eigenvectors of a full or band complex Hermitian matrix can also be found if CHETRD or CHPTRD or CHBTRD has been used to reduce this matrix to tridiagonal form. ARGUMENTS COMPZ (input) = 'N': Compute eigenvalues only. = 'V': Compute eigenvalues and eigenvectors of the original Hermitian matrix. On entry, Z must contain the unitary matrix used to reduce the original matrix to tridiagonal form. = 'I': Compute eigenvalues and eigenvectors of the tridiagonal matrix. Z is initialized to the identity matrix. N (input) The order of the matrix. N >= 0. D (input/output) On entry, the diagonal elements of the tridiagonal matrix. On exit, if INFO = 0, the eigenvalues in ascending order. E (input/output) On entry, the (n-1) subdiagonal elements of the tridiagonal matrix. On exit, E has been destroyed. Z (input) On entry, if COMPZ = 'V', then Z contains the unitary matrix used in the reduction to tridiagonal form. On exit, if INFO = 0, then if COMPZ = 'V', Z contains the orthonormal eigen- vectors of the original Hermitian matrix, and if COMPZ = 'I', Z contains the orthonormal eigenvectors of the symmetric tridiagonal matrix. If COMPZ = 'N', then Z is not refer- enced. LDZ (input) The leading dimension of the array Z. LDZ >= 1, and if eigenvectors are desired, then LDZ >= max(1,N). WORK (workspace) dimension(max(1,2*N-2)) If COMPZ = 'N', then WORK is not ref- erenced. INFO (output) = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: the algorithm has failed to find all the eigenvalues in a total of 30*N iterations; if INFO = i, then i elements of E have not converged to zero; on exit, D and E contain the ele- ments of a symmetric tridiagonal matrix which is unitarily similar to the original matrix. 7 Nov 2015 zsteqr(3P)