#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int chpevd_(char *jobz, char *uplo, integer *n, complex *ap, real *w, complex *z__, integer *ldz, complex *work, integer *lwork, real *rwork, integer *lrwork, integer *iwork, integer *liwork, integer *info) { /* -- LAPACK driver routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University June 30, 1999 Purpose ======= CHPEVD computes all the eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A in packed storage. 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. AP (input/output) COMPLEX array, dimension (N*(N+1)/2) On entry, the upper or lower triangle of the Hermitian matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n. On exit, AP is overwritten by values generated during the reduction to tridiagonal form. If UPLO = 'U', the diagonal and first superdiagonal of the tridiagonal matrix T overwrite the corresponding elements of A, and if UPLO = 'L', the diagonal and first subdiagonal of T overwrite the corresponding elements of A. W (output) REAL array, dimension (N) If INFO = 0, the eigenvalues in ascending order. Z (output) COMPLEX array, dimension (LDZ, N) If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal eigenvectors of the matrix A, with the i-th column of Z holding the eigenvector associated with W(i). If JOBZ = 'N', then Z is not referenced. LDZ (input) INTEGER The leading dimension of the array Z. LDZ >= 1, and if JOBZ = 'V', LDZ >= max(1,N). WORK (workspace/output) COMPLEX array, dimension (LWORK) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. LWORK (input) INTEGER The dimension of array WORK. If N <= 1, LWORK must be at least 1. If JOBZ = 'N' and N > 1, LWORK must be at least N. If JOBZ = 'V' and N > 1, LWORK must be at least 2*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. RWORK (workspace/output) REAL array, dimension (LRWORK) On exit, if INFO = 0, RWORK(1) returns the optimal LRWORK. LRWORK (input) INTEGER The dimension of 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 size of the RWORK array, returns this value as the first entry of the RWORK array, and no error message related to LRWORK 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 array IWORK. If JOBZ = 'N' or 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 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 = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value. > 0: if INFO = i, the algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero. ===================================================================== Test the input parameters. Parameter adjustments */ /* Table of constant values */ static integer c__1 = 1; /* System generated locals */ integer z_dim1, z_offset, i__1; real r__1; /* Builtin functions */ double sqrt(doublereal); /* Local variables */ static integer inde; static real anrm; static integer imax; static real rmin, rmax, sigma; extern logical lsame_(char *, char *); static integer iinfo; extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); static integer lwmin, llrwk, llwrk; static logical wantz; static integer iscale; extern doublereal clanhp_(char *, char *, integer *, complex *, real *); extern /* Subroutine */ int cstedc_(char *, integer *, real *, real *, complex *, integer *, complex *, integer *, real *, integer *, integer *, integer *, integer *); extern doublereal slamch_(char *); extern /* Subroutine */ int csscal_(integer *, real *, complex *, integer *); static real safmin; extern /* Subroutine */ int xerbla_(char *, integer *); static real bignum; static integer indtau; extern /* Subroutine */ int chptrd_(char *, integer *, complex *, real *, real *, complex *, integer *); static integer indrwk, indwrk, liwmin; extern /* Subroutine */ int ssterf_(integer *, real *, real *, integer *); static integer lrwmin; extern /* Subroutine */ int cupmtr_(char *, char *, char *, integer *, integer *, complex *, complex *, complex *, integer *, complex *, integer *); static real smlnum; static logical lquery; static real eps; #define z___subscr(a_1,a_2) (a_2)*z_dim1 + a_1 #define z___ref(a_1,a_2) z__[z___subscr(a_1,a_2)] --ap; --w; z_dim1 = *ldz; z_offset = 1 + z_dim1 * 1; z__ -= z_offset; --work; --rwork; --iwork; /* Function Body */ wantz = lsame_(jobz, "V"); lquery = *lwork == -1 || *lrwork == -1 || *liwork == -1; *info = 0; if (*n <= 1) { lwmin = 1; liwmin = 1; lrwmin = 1; } else { if (wantz) { lwmin = *n << 1; /* Computing 2nd power */ i__1 = *n; lrwmin = *n * 5 + 1 + (i__1 * i__1 << 1); liwmin = *n * 5 + 3; } else { lwmin = *n; lrwmin = *n; liwmin = 1; } } if (! (wantz || lsame_(jobz, "N"))) { *info = -1; } else if (! (lsame_(uplo, "L") || lsame_(uplo, "U"))) { *info = -2; } else if (*n < 0) { *info = -3; } else if (*ldz < 1 || wantz && *ldz < *n) { *info = -7; } else if (*lwork < lwmin && ! lquery) { *info = -9; } else if (*lrwork < lrwmin && ! lquery) { *info = -11; } else if (*liwork < liwmin && ! lquery) { *info = -13; } if (*info == 0) { work[1].r = (real) lwmin, work[1].i = 0.f; rwork[1] = (real) lrwmin; iwork[1] = liwmin; } if (*info != 0) { i__1 = -(*info); xerbla_("CHPEVD", &i__1); return 0; } /* Quick return if possible */ if (*n == 0) { return 0; } if (*n == 1) { w[1] = ap[1].r; if (wantz) { i__1 = z___subscr(1, 1); z__[i__1].r = 1.f, z__[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 = clanhp_("M", uplo, n, &ap[1], &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) { i__1 = *n * (*n + 1) / 2; csscal_(&i__1, &sigma, &ap[1], &c__1); } /* Call CHPTRD to reduce Hermitian packed matrix to tridiagonal form. */ inde = 1; indtau = 1; indrwk = inde + *n; indwrk = indtau + *n; llwrk = *lwork - indwrk + 1; llrwk = *lrwork - indrwk + 1; chptrd_(uplo, n, &ap[1], &w[1], &rwork[inde], &work[indtau], &iinfo); /* For eigenvalues only, call SSTERF. For eigenvectors, first call CUPGTR to generate the orthogonal matrix, then call CSTEDC. */ if (! wantz) { ssterf_(n, &w[1], &rwork[inde], info); } else { cstedc_("I", n, &w[1], &rwork[inde], &z__[z_offset], ldz, &work[ indwrk], &llwrk, &rwork[indrwk], &llrwk, &iwork[1], liwork, info); cupmtr_("L", uplo, "N", n, n, &ap[1], &work[indtau], &z__[z_offset], ldz, &work[indwrk], &iinfo); } /* 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) lwmin, work[1].i = 0.f; rwork[1] = (real) lrwmin; iwork[1] = liwmin; return 0; /* End of CHPEVD */ } /* chpevd_ */ #undef z___ref #undef z___subscr