#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int cheevd_(char *jobz, char *uplo, integer *n, complex *a, integer *lda, real *w, complex *work, integer *lwork, real *rwork, integer *lrwork, integer *iwork, integer *liwork, integer *info) { /* -- LAPACK driver routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= CHEEVD computes all eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A. If eigenvectors are desired, it uses a divide and conquer algorithm. 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. Arguments ========= JOBZ (input) CHARACTER*1 = 'N': Compute eigenvalues only; = 'V': Compute eigenvalues and eigenvectors. UPLO (input) CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. N (input) INTEGER The order of the matrix A. N >= 0. A (input/output) COMPLEX array, dimension (LDA, N) On entry, the Hermitian matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A. On exit, if JOBZ = 'V', then if INFO = 0, A contains the orthonormal eigenvectors of the matrix A. If JOBZ = 'N', then on exit the lower triangle (if UPLO='L') or the upper triangle (if UPLO='U') of A, including the diagonal, is destroyed. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,N). W (output) REAL array, dimension (N) If INFO = 0, the eigenvalues in ascending order. WORK (workspace/output) COMPLEX array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. LWORK (input) INTEGER The length of the array WORK. If N <= 1, LWORK must be at least 1. If JOBZ = 'N' and N > 1, LWORK must be at least N + 1. If JOBZ = 'V' and N > 1, LWORK must be at least 2*N + N**2. If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal sizes of the WORK, RWORK and IWORK arrays, returns these values as the first entries of the WORK, RWORK and IWORK arrays, and no error message related to LWORK or LRWORK or LIWORK is issued by XERBLA. RWORK (workspace/output) REAL array, dimension (LRWORK) On exit, if INFO = 0, RWORK(1) returns the optimal LRWORK. LRWORK (input) INTEGER The dimension of the array RWORK. If N <= 1, LRWORK must be at least 1. If JOBZ = 'N' and N > 1, LRWORK must be at least N. If JOBZ = 'V' and N > 1, LRWORK must be at least 1 + 5*N + 2*N**2. If LRWORK = -1, then a workspace query is assumed; the routine only calculates the optimal sizes of the WORK, RWORK and IWORK arrays, returns these values as the first entries of the WORK, RWORK and IWORK arrays, and no error message related to LWORK or LRWORK or LIWORK is issued by XERBLA. IWORK (workspace/output) INTEGER array, dimension (MAX(1,LIWORK)) On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK. LIWORK (input) INTEGER The dimension of the array IWORK. If N <= 1, LIWORK must be at least 1. If JOBZ = 'N' and N > 1, LIWORK must be at least 1. If JOBZ = 'V' and N > 1, LIWORK must be at least 3 + 5*N. If LIWORK = -1, then a workspace query is assumed; the routine only calculates the optimal sizes of the WORK, RWORK and IWORK arrays, returns these values as the first entries of the WORK, RWORK and IWORK arrays, and no error message related to LWORK or LRWORK or LIWORK is issued by XERBLA. INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i and JOBZ = 'N', then the algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero; if INFO = i and JOBZ = 'V', then the algorithm failed to compute an eigenvalue while working on the submatrix lying in rows and columns INFO/(N+1) through mod(INFO,N+1). Further Details =============== Based on contributions by Jeff Rutter, Computer Science Division, University of California at Berkeley, USA Modified description of INFO. Sven, 16 Feb 05. ===================================================================== Test the input parameters. Parameter adjustments */ /* Table of constant values */ static integer c__1 = 1; static integer c_n1 = -1; static integer c__0 = 0; static real c_b18 = 1.f; /* System generated locals */ integer a_dim1, a_offset, i__1, i__2; real r__1; /* Builtin functions */ double sqrt(doublereal); /* Local variables */ static real eps; static integer inde; static real anrm; static integer imax; static real rmin, rmax; static integer lopt; static real sigma; extern logical lsame_(char *, char *); static integer iinfo; extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); static integer lwmin, liopt; static logical lower; static integer llrwk, lropt; static logical wantz; static integer indwk2, llwrk2; extern doublereal clanhe_(char *, char *, integer *, complex *, integer *, real *); static integer iscale; extern /* Subroutine */ int clascl_(char *, integer *, integer *, real *, real *, integer *, integer *, complex *, integer *, integer *), cstedc_(char *, integer *, real *, real *, complex *, integer *, complex *, integer *, real *, integer *, integer *, integer *, integer *); extern doublereal slamch_(char *); extern /* Subroutine */ int chetrd_(char *, integer *, complex *, integer *, real *, real *, complex *, complex *, integer *, integer *), clacpy_(char *, integer *, integer *, complex *, integer *, complex *, integer *); static real safmin; extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *, ftnlen, ftnlen); extern /* Subroutine */ int xerbla_(char *, integer *); static real bignum; static integer indtau, indrwk, indwrk, liwmin; extern /* Subroutine */ int ssterf_(integer *, real *, real *, integer *); static integer lrwmin; extern /* Subroutine */ int cunmtr_(char *, char *, char *, integer *, integer *, complex *, integer *, complex *, complex *, integer *, complex *, integer *, integer *); static integer llwork; static real smlnum; static logical lquery; a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; --w; --work; --rwork; --iwork; /* Function Body */ wantz = lsame_(jobz, "V"); lower = lsame_(uplo, "L"); lquery = *lwork == -1 || *lrwork == -1 || *liwork == -1; *info = 0; if (! (wantz || lsame_(jobz, "N"))) { *info = -1; } else if (! (lower || lsame_(uplo, "U"))) { *info = -2; } else if (*n < 0) { *info = -3; } else if (*lda < max(1,*n)) { *info = -5; } if (*info == 0) { if (*n <= 1) { lwmin = 1; lrwmin = 1; liwmin = 1; lopt = lwmin; lropt = lrwmin; liopt = liwmin; } else { if (wantz) { lwmin = (*n << 1) + *n * *n; /* Computing 2nd power */ i__1 = *n; lrwmin = *n * 5 + 1 + (i__1 * i__1 << 1); liwmin = *n * 5 + 3; } else { lwmin = *n + 1; lrwmin = *n; liwmin = 1; } /* Computing MAX */ i__1 = lwmin, i__2 = *n + ilaenv_(&c__1, "CHETRD", uplo, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, (ftnlen)1); lopt = max(i__1,i__2); lropt = lrwmin; liopt = liwmin; } work[1].r = (real) lopt, work[1].i = 0.f; rwork[1] = (real) lropt; iwork[1] = liopt; if (*lwork < lwmin && ! lquery) { *info = -8; } else if (*lrwork < lrwmin && ! lquery) { *info = -10; } else if (*liwork < liwmin && ! lquery) { *info = -12; } } if (*info != 0) { i__1 = -(*info); xerbla_("CHEEVD", &i__1); return 0; } else if (lquery) { return 0; } /* Quick return if possible */ if (*n == 0) { return 0; } if (*n == 1) { i__1 = a_dim1 + 1; w[1] = a[i__1].r; if (wantz) { i__1 = a_dim1 + 1; a[i__1].r = 1.f, a[i__1].i = 0.f; } return 0; } /* Get machine constants. */ safmin = slamch_("Safe minimum"); eps = slamch_("Precision"); smlnum = safmin / eps; bignum = 1.f / smlnum; rmin = sqrt(smlnum); rmax = sqrt(bignum); /* Scale matrix to allowable range, if necessary. */ anrm = clanhe_("M", uplo, n, &a[a_offset], lda, &rwork[1]); iscale = 0; if (anrm > 0.f && anrm < rmin) { iscale = 1; sigma = rmin / anrm; } else if (anrm > rmax) { iscale = 1; sigma = rmax / anrm; } if (iscale == 1) { clascl_(uplo, &c__0, &c__0, &c_b18, &sigma, n, n, &a[a_offset], lda, info); } /* Call CHETRD to reduce Hermitian matrix to tridiagonal form. */ inde = 1; indtau = 1; indwrk = indtau + *n; indrwk = inde + *n; indwk2 = indwrk + *n * *n; llwork = *lwork - indwrk + 1; llwrk2 = *lwork - indwk2 + 1; llrwk = *lrwork - indrwk + 1; chetrd_(uplo, n, &a[a_offset], lda, &w[1], &rwork[inde], &work[indtau], & work[indwrk], &llwork, &iinfo); /* For eigenvalues only, call SSTERF. For eigenvectors, first call CSTEDC to generate the eigenvector matrix, WORK(INDWRK), of the tridiagonal matrix, then call CUNMTR to multiply it to the Householder transformations represented as Householder vectors in A. */ if (! wantz) { ssterf_(n, &w[1], &rwork[inde], info); } else { cstedc_("I", n, &w[1], &rwork[inde], &work[indwrk], n, &work[indwk2], &llwrk2, &rwork[indrwk], &llrwk, &iwork[1], liwork, info); cunmtr_("L", uplo, "N", n, n, &a[a_offset], lda, &work[indtau], &work[ indwrk], n, &work[indwk2], &llwrk2, &iinfo); clacpy_("A", n, n, &work[indwrk], n, &a[a_offset], lda); } /* If matrix was scaled, then rescale eigenvalues appropriately. */ if (iscale == 1) { if (*info == 0) { imax = *n; } else { imax = *info - 1; } r__1 = 1.f / sigma; sscal_(&imax, &r__1, &w[1], &c__1); } work[1].r = (real) lopt, work[1].i = 0.f; rwork[1] = (real) lropt; iwork[1] = liopt; return 0; /* End of CHEEVD */ } /* cheevd_ */