#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int chegv_(integer *itype, char *jobz, char *uplo, integer * n, complex *a, integer *lda, complex *b, integer *ldb, real *w, complex *work, integer *lwork, real *rwork, integer *info ) { /* -- LAPACK driver routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= CHEGV computes all the eigenvalues, and optionally, the eigenvectors of a complex generalized Hermitian-definite eigenproblem, of the form A*x=(lambda)*B*x, A*Bx=(lambda)*x, or B*A*x=(lambda)*x. Here A and B are assumed to be Hermitian and B is also positive definite. Arguments ========= ITYPE (input) INTEGER Specifies the problem type to be solved: = 1: A*x = (lambda)*B*x = 2: A*B*x = (lambda)*x = 3: B*A*x = (lambda)*x JOBZ (input) CHARACTER*1 = 'N': Compute eigenvalues only; = 'V': Compute eigenvalues and eigenvectors. UPLO (input) CHARACTER*1 = 'U': Upper triangles of A and B are stored; = 'L': Lower triangles of A and B are stored. N (input) INTEGER The order of the matrices A and B. 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 matrix Z of eigenvectors. The eigenvectors are normalized as follows: if ITYPE = 1 or 2, Z**H*B*Z = I; if ITYPE = 3, Z**H*inv(B)*Z = I. If JOBZ = 'N', then on exit the upper triangle (if UPLO='U') or the lower triangle (if UPLO='L') of A, including the diagonal, is destroyed. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,N). B (input/output) COMPLEX array, dimension (LDB, N) On entry, the Hermitian positive definite matrix B. If UPLO = 'U', the leading N-by-N upper triangular part of B contains the upper triangular part of the matrix B. If UPLO = 'L', the leading N-by-N lower triangular part of B contains the lower triangular part of the matrix B. On exit, if INFO <= N, the part of B containing the matrix is overwritten by the triangular factor U or L from the Cholesky factorization B = U**H*U or B = L*L**H. LDB (input) INTEGER The leading dimension of the array B. LDB >= 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. LWORK >= max(1,2*N-1). For optimal efficiency, LWORK >= (NB+1)*N, where NB is the blocksize for CHETRD returned by ILAENV. 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) REAL array, dimension (max(1, 3*N-2)) INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: CPOTRF or CHEEV returned an error code: <= N: if INFO = i, CHEEV failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero; > N: if INFO = N + i, for 1 <= i <= N, then the leading minor of order i of B is not positive definite. The factorization of B could not be completed and no eigenvalues or eigenvectors were computed. ===================================================================== Test the input parameters. Parameter adjustments */ /* Table of constant values */ static complex c_b1 = {1.f,0.f}; static integer c__1 = 1; static integer c_n1 = -1; /* System generated locals */ integer a_dim1, a_offset, b_dim1, b_offset, i__1, i__2; /* Local variables */ static integer nb, neig; extern /* Subroutine */ int cheev_(char *, char *, integer *, complex *, integer *, real *, complex *, integer *, real *, integer *); extern logical lsame_(char *, char *); extern /* Subroutine */ int ctrmm_(char *, char *, char *, char *, integer *, integer *, complex *, complex *, integer *, complex *, integer *); static char trans[1]; extern /* Subroutine */ int ctrsm_(char *, char *, char *, char *, integer *, integer *, complex *, complex *, integer *, complex *, integer *); static logical upper, wantz; extern /* Subroutine */ int chegst_(integer *, char *, integer *, complex *, integer *, complex *, integer *, integer *); extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *, ftnlen, ftnlen); extern /* Subroutine */ int xerbla_(char *, integer *), cpotrf_( char *, integer *, complex *, integer *, integer *); static integer lwkopt; static logical lquery; a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; b_dim1 = *ldb; b_offset = 1 + b_dim1; b -= b_offset; --w; --work; --rwork; /* Function Body */ wantz = lsame_(jobz, "V"); upper = lsame_(uplo, "U"); lquery = *lwork == -1; *info = 0; if (*itype < 1 || *itype > 3) { *info = -1; } else if (! (wantz || lsame_(jobz, "N"))) { *info = -2; } else if (! (upper || lsame_(uplo, "L"))) { *info = -3; } else if (*n < 0) { *info = -4; } else if (*lda < max(1,*n)) { *info = -6; } else if (*ldb < max(1,*n)) { *info = -8; } if (*info == 0) { nb = ilaenv_(&c__1, "CHETRD", uplo, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, (ftnlen)1); /* Computing MAX */ i__1 = 1, i__2 = (nb + 1) * *n; lwkopt = max(i__1,i__2); work[1].r = (real) lwkopt, work[1].i = 0.f; /* Computing MAX */ i__1 = 1, i__2 = (*n << 1) - 1; if (*lwork < max(i__1,i__2) && ! lquery) { *info = -11; } } if (*info != 0) { i__1 = -(*info); xerbla_("CHEGV ", &i__1); return 0; } else if (lquery) { return 0; } /* Quick return if possible */ if (*n == 0) { return 0; } /* Form a Cholesky factorization of B. */ cpotrf_(uplo, n, &b[b_offset], ldb, info); if (*info != 0) { *info = *n + *info; return 0; } /* Transform problem to standard eigenvalue problem and solve. */ chegst_(itype, uplo, n, &a[a_offset], lda, &b[b_offset], ldb, info); cheev_(jobz, uplo, n, &a[a_offset], lda, &w[1], &work[1], lwork, &rwork[1] , info); if (wantz) { /* Backtransform eigenvectors to the original problem. */ neig = *n; if (*info > 0) { neig = *info - 1; } if (*itype == 1 || *itype == 2) { /* For A*x=(lambda)*B*x and A*B*x=(lambda)*x; backtransform eigenvectors: x = inv(L)'*y or inv(U)*y */ if (upper) { *(unsigned char *)trans = 'N'; } else { *(unsigned char *)trans = 'C'; } ctrsm_("Left", uplo, trans, "Non-unit", n, &neig, &c_b1, &b[ b_offset], ldb, &a[a_offset], lda); } else if (*itype == 3) { /* For B*A*x=(lambda)*x; backtransform eigenvectors: x = L*y or U'*y */ if (upper) { *(unsigned char *)trans = 'C'; } else { *(unsigned char *)trans = 'N'; } ctrmm_("Left", uplo, trans, "Non-unit", n, &neig, &c_b1, &b[ b_offset], ldb, &a[a_offset], lda); } } work[1].r = (real) lwkopt, work[1].i = 0.f; return 0; /* End of CHEGV */ } /* chegv_ */