#include "f2c.h" #include "blaswrap.h" /* Subroutine */ int zstegr_(char *jobz, char *range, integer *n, doublereal * d__, doublereal *e, doublereal *vl, doublereal *vu, integer *il, integer *iu, doublereal *abstol, integer *m, doublereal *w, doublecomplex *z__, integer *ldz, integer *isuppz, doublereal *work, integer *lwork, integer *iwork, integer *liwork, integer *info) { /* System generated locals */ integer z_dim1, z_offset; /* Local variables */ logical tryrac; extern /* Subroutine */ int zstemr_(char *, char *, integer *, doublereal *, doublereal *, doublereal *, doublereal *, integer *, integer *, integer *, doublereal *, doublecomplex *, integer *, integer *, integer *, logical *, doublereal *, integer *, integer *, integer *, integer *); /* -- LAPACK computational routine (version 3.1) -- */ /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ /* November 2006 */ /* .. Scalar Arguments .. */ /* .. */ /* .. Array Arguments .. */ /* .. */ /* Purpose */ /* ======= */ /* ZSTEGR computes selected eigenvalues and, optionally, eigenvectors */ /* of a real symmetric tridiagonal matrix T. Any such unreduced matrix has */ /* a well defined set of pairwise different real eigenvalues, the corresponding */ /* real eigenvectors are pairwise orthogonal. */ /* The spectrum may be computed either completely or partially by specifying */ /* either an interval (VL,VU] or a range of indices IL:IU for the desired */ /* eigenvalues. */ /* ZSTEGR is a compatability wrapper around the improved ZSTEMR routine. */ /* See DSTEMR for further details. */ /* One important change is that the ABSTOL parameter no longer provides any */ /* benefit and hence is no longer used. */ /* Note : ZSTEGR and ZSTEMR work only on machines which follow */ /* IEEE-754 floating-point standard in their handling of infinities and */ /* NaNs. Normal execution may create these exceptiona values and hence */ /* may abort due to a floating point exception in environments which */ /* do not conform to the IEEE-754 standard. */ /* Arguments */ /* ========= */ /* JOBZ (input) CHARACTER*1 */ /* = 'N': Compute eigenvalues only; */ /* = 'V': Compute eigenvalues and eigenvectors. */ /* RANGE (input) CHARACTER*1 */ /* = 'A': all eigenvalues will be found. */ /* = 'V': all eigenvalues in the half-open interval (VL,VU] */ /* will be found. */ /* = 'I': the IL-th through IU-th eigenvalues will be found. */ /* N (input) INTEGER */ /* The order of the matrix. N >= 0. */ /* D (input/output) DOUBLE PRECISION array, dimension (N) */ /* On entry, the N diagonal elements of the tridiagonal matrix */ /* T. On exit, D is overwritten. */ /* E (input/output) DOUBLE PRECISION array, dimension (N) */ /* On entry, the (N-1) subdiagonal elements of the tridiagonal */ /* matrix T in elements 1 to N-1 of E. E(N) need not be set on */ /* input, but is used internally as workspace. */ /* On exit, E is overwritten. */ /* VL (input) DOUBLE PRECISION */ /* VU (input) DOUBLE PRECISION */ /* If RANGE='V', the lower and upper bounds of the interval to */ /* be searched for eigenvalues. VL < VU. */ /* Not referenced if RANGE = 'A' or 'I'. */ /* IL (input) INTEGER */ /* IU (input) INTEGER */ /* If RANGE='I', the indices (in ascending order) of the */ /* smallest and largest eigenvalues to be returned. */ /* 1 <= IL <= IU <= N, if N > 0. */ /* Not referenced if RANGE = 'A' or 'V'. */ /* ABSTOL (input) DOUBLE PRECISION */ /* Unused. Was the absolute error tolerance for the */ /* eigenvalues/eigenvectors in previous versions. */ /* M (output) INTEGER */ /* The total number of eigenvalues found. 0 <= M <= N. */ /* If RANGE = 'A', M = N, and if RANGE = 'I', M = IU-IL+1. */ /* W (output) DOUBLE PRECISION array, dimension (N) */ /* The first M elements contain the selected eigenvalues in */ /* ascending order. */ /* Z (output) COMPLEX*16 array, dimension (LDZ, max(1,M) ) */ /* If JOBZ = 'V', and if INFO = 0, then the first M columns of Z */ /* contain the orthonormal eigenvectors of the matrix T */ /* corresponding to the selected eigenvalues, with the i-th */ /* column of Z holding the eigenvector associated with W(i). */ /* If JOBZ = 'N', then Z is not referenced. */ /* Note: the user must ensure that at least max(1,M) columns are */ /* supplied in the array Z; if RANGE = 'V', the exact value of M */ /* is not known in advance and an upper bound must be used. */ /* Supplying N columns is always safe. */ /* LDZ (input) INTEGER */ /* The leading dimension of the array Z. LDZ >= 1, and if */ /* JOBZ = 'V', then LDZ >= max(1,N). */ /* ISUPPZ (output) INTEGER ARRAY, dimension ( 2*max(1,M) ) */ /* The support of the eigenvectors in Z, i.e., the indices */ /* indicating the nonzero elements in Z. The i-th computed eigenvector */ /* is nonzero only in elements ISUPPZ( 2*i-1 ) through */ /* ISUPPZ( 2*i ). This is relevant in the case when the matrix */ /* is split. ISUPPZ is only accessed when JOBZ is 'V' and N > 0. */ /* WORK (workspace/output) DOUBLE PRECISION array, dimension (LWORK) */ /* On exit, if INFO = 0, WORK(1) returns the optimal */ /* (and minimal) LWORK. */ /* LWORK (input) INTEGER */ /* The dimension of the array WORK. LWORK >= max(1,18*N) */ /* if JOBZ = 'V', and LWORK >= max(1,12*N) if JOBZ = 'N'. */ /* 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. */ /* IWORK (workspace/output) INTEGER array, dimension (LIWORK) */ /* On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK. */ /* LIWORK (input) INTEGER */ /* The dimension of the array IWORK. LIWORK >= max(1,10*N) */ /* if the eigenvectors are desired, and LIWORK >= max(1,8*N) */ /* if only the eigenvalues are to be computed. */ /* 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. */ /* INFO (output) INTEGER */ /* On exit, INFO */ /* = 0: successful exit */ /* < 0: if INFO = -i, the i-th argument had an illegal value */ /* > 0: if INFO = 1X, internal error in DLARRE, */ /* if INFO = 2X, internal error in ZLARRV. */ /* Here, the digit X = ABS( IINFO ) < 10, where IINFO is */ /* the nonzero error code returned by DLARRE or */ /* ZLARRV, respectively. */ /* Further Details */ /* =============== */ /* Based on contributions by */ /* Inderjit Dhillon, IBM Almaden, USA */ /* Osni Marques, LBNL/NERSC, USA */ /* Christof Voemel, LBNL/NERSC, USA */ /* ===================================================================== */ /* .. Local Scalars .. */ /* .. */ /* .. External Subroutines .. */ /* .. */ /* .. Executable Statements .. */ /* Parameter adjustments */ --d__; --e; --w; z_dim1 = *ldz; z_offset = 1 + z_dim1; z__ -= z_offset; --isuppz; --work; --iwork; /* Function Body */ *info = 0; tryrac = FALSE_; zstemr_(jobz, range, n, &d__[1], &e[1], vl, vu, il, iu, m, &w[1], &z__[ z_offset], ldz, n, &isuppz[1], &tryrac, &work[1], lwork, &iwork[1] , liwork, info); /* End of ZSTEGR */ return 0; } /* zstegr_ */