#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int dgegv_(char *jobvl, char *jobvr, integer *n, doublereal * a, integer *lda, doublereal *b, integer *ldb, doublereal *alphar, doublereal *alphai, doublereal *beta, doublereal *vl, integer *ldvl, doublereal *vr, integer *ldvr, doublereal *work, integer *lwork, 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Institute, Argonne National Lab, and Rice University June 30, 1999 Purpose ======= This routine is deprecated and has been replaced by routine DGGEV. DGEGV computes for a pair of n-by-n real nonsymmetric matrices A and B, the generalized eigenvalues (alphar +/- alphai*i, beta), and optionally, the left and/or right generalized eigenvectors (VL and VR). A generalized eigenvalue for a pair of matrices (A,B) is, roughly speaking, a scalar w or a ratio alpha/beta = w, such that A - w*B is singular. It is usually represented as the pair (alpha,beta), as there is a reasonable interpretation for beta=0, and even for both being zero. A good beginning reference is the book, "Matrix Computations", by G. Golub & C. van Loan (Johns Hopkins U. Press) A right generalized eigenvector corresponding to a generalized eigenvalue w for a pair of matrices (A,B) is a vector r such that (A - w B) r = 0 . A left generalized eigenvector is a vector l such that l**H * (A - w B) = 0, where l**H is the conjugate-transpose of l. Note: this routine performs "full balancing" on A and B -- see "Further Details", below. Arguments ========= JOBVL (input) CHARACTER*1 = 'N': do not compute the left generalized eigenvectors; = 'V': compute the left generalized eigenvectors. JOBVR (input) CHARACTER*1 = 'N': do not compute the right generalized eigenvectors; = 'V': compute the right generalized eigenvectors. N (input) INTEGER The order of the matrices A, B, VL, and VR. N >= 0. A (input/output) DOUBLE PRECISION array, dimension (LDA, N) On entry, the first of the pair of matrices whose generalized eigenvalues and (optionally) generalized eigenvectors are to be computed. On exit, the contents will have been destroyed. (For a description of the contents of A on exit, see "Further Details", below.) LDA (input) INTEGER The leading dimension of A. LDA >= max(1,N). B (input/output) DOUBLE PRECISION array, dimension (LDB, N) On entry, the second of the pair of matrices whose generalized eigenvalues and (optionally) generalized eigenvectors are to be computed. On exit, the contents will have been destroyed. (For a description of the contents of B on exit, see "Further Details", below.) LDB (input) INTEGER The leading dimension of B. LDB >= max(1,N). ALPHAR (output) DOUBLE PRECISION array, dimension (N) ALPHAI (output) DOUBLE PRECISION array, dimension (N) BETA (output) DOUBLE PRECISION array, dimension (N) On exit, (ALPHAR(j) + ALPHAI(j)*i)/BETA(j), j=1,...,N, will be the generalized eigenvalues. If ALPHAI(j) is zero, then the j-th eigenvalue is real; if positive, then the j-th and (j+1)-st eigenvalues are a complex conjugate pair, with ALPHAI(j+1) negative. Note: the quotients ALPHAR(j)/BETA(j) and ALPHAI(j)/BETA(j) may easily over- or underflow, and BETA(j) may even be zero. Thus, the user should avoid naively computing the ratio alpha/beta. However, ALPHAR and ALPHAI will be always less than and usually comparable with norm(A) in magnitude, and BETA always less than and usually comparable with norm(B). VL (output) DOUBLE PRECISION array, dimension (LDVL,N) If JOBVL = 'V', the left generalized eigenvectors. (See "Purpose", above.) Real eigenvectors take one column, complex take two columns, the first for the real part and the second for the imaginary part. Complex eigenvectors correspond to an eigenvalue with positive imaginary part. Each eigenvector will be scaled so the largest component will have abs(real part) + abs(imag. part) = 1, *except* that for eigenvalues with alpha=beta=0, a zero vector will be returned as the corresponding eigenvector. Not referenced if JOBVL = 'N'. LDVL (input) INTEGER The leading dimension of the matrix VL. LDVL >= 1, and if JOBVL = 'V', LDVL >= N. VR (output) DOUBLE PRECISION array, dimension (LDVR,N) If JOBVR = 'V', the right generalized eigenvectors. (See "Purpose", above.) Real eigenvectors take one column, complex take two columns, the first for the real part and the second for the imaginary part. Complex eigenvectors correspond to an eigenvalue with positive imaginary part. Each eigenvector will be scaled so the largest component will have abs(real part) + abs(imag. part) = 1, *except* that for eigenvalues with alpha=beta=0, a zero vector will be returned as the corresponding eigenvector. Not referenced if JOBVR = 'N'. LDVR (input) INTEGER The leading dimension of the matrix VR. LDVR >= 1, and if JOBVR = 'V', LDVR >= N. WORK (workspace/output) DOUBLE PRECISION array, dimension (LWORK) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. LWORK (input) INTEGER The dimension of the array WORK. LWORK >= max(1,8*N). For good performance, LWORK must generally be larger. To compute the optimal value of LWORK, call ILAENV to get blocksizes (for DGEQRF, DORMQR, and DORGQR.) Then compute: NB -- MAX of the blocksizes for DGEQRF, DORMQR, and DORGQR; The optimal LWORK is: 2*N + MAX( 6*N, N*(NB+1) ). 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. INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value. = 1,...,N: The QZ iteration failed. No eigenvectors have been calculated, but ALPHAR(j), ALPHAI(j), and BETA(j) should be correct for j=INFO+1,...,N. > N: errors that usually indicate LAPACK problems: =N+1: error return from DGGBAL =N+2: error return from DGEQRF =N+3: error return from DORMQR =N+4: error return from DORGQR =N+5: error return from DGGHRD =N+6: error return from DHGEQZ (other than failed iteration) =N+7: error return from DTGEVC =N+8: error return from DGGBAK (computing VL) =N+9: error return from DGGBAK (computing VR) =N+10: error return from DLASCL (various calls) Further Details =============== Balancing --------- This driver calls DGGBAL to both permute and scale rows and columns of A and B. The permutations PL and PR are chosen so that PL*A*PR and PL*B*R will be upper triangular except for the diagonal blocks A(i:j,i:j) and B(i:j,i:j), with i and j as close together as possible. The diagonal scaling matrices DL and DR are chosen so that the pair DL*PL*A*PR*DR, DL*PL*B*PR*DR have elements close to one (except for the elements that start out zero.) After the eigenvalues and eigenvectors of the balanced matrices have been computed, DGGBAK transforms the eigenvectors back to what they would have been (in perfect arithmetic) if they had not been balanced. Contents of A and B on Exit -------- -- - --- - -- ---- If any eigenvectors are computed (either JOBVL='V' or JOBVR='V' or both), then on exit the arrays A and B will contain the real Schur form[*] of the "balanced" versions of A and B. If no eigenvectors are computed, then only the diagonal blocks will be correct. [*] See DHGEQZ, DGEGS, or read the book "Matrix Computations", by Golub & van Loan, pub. by Johns Hopkins U. Press. ===================================================================== Decode the input arguments Parameter adjustments */ /* Table of constant values */ static integer c__1 = 1; static integer c_n1 = -1; static doublereal c_b27 = 1.; static doublereal c_b38 = 0.; /* System generated locals */ integer a_dim1, a_offset, b_dim1, b_offset, vl_dim1, vl_offset, vr_dim1, vr_offset, i__1, i__2; doublereal d__1, d__2, d__3, d__4; /* Local variables */ static doublereal absb, anrm, bnrm; static integer itau; static doublereal temp; static logical ilvl, ilvr; static integer lopt; static doublereal anrm1, anrm2, bnrm1, bnrm2, absai, scale, absar, sbeta; extern logical lsame_(char *, char *); static integer ileft, iinfo, icols, iwork, irows, jc; extern /* Subroutine */ int dggbak_(char *, char *, integer *, integer *, integer *, doublereal *, doublereal *, integer *, doublereal *, integer *, integer *); static integer nb; extern /* Subroutine */ int dggbal_(char *, integer *, doublereal *, integer *, doublereal *, integer *, integer *, integer *, doublereal *, doublereal *, doublereal *, integer *); static integer in; extern doublereal dlamch_(char *), dlange_(char *, integer *, integer *, doublereal *, integer *, doublereal *); static integer jr; static doublereal salfai; extern /* Subroutine */ int dgghrd_(char *, char *, integer *, integer *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, integer *), dlascl_(char *, integer *, integer *, doublereal *, doublereal *, integer *, integer *, doublereal *, integer *, integer *); static doublereal salfar; extern /* Subroutine */ int dgeqrf_(integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, integer *), dlacpy_(char *, integer *, integer *, doublereal *, integer *, doublereal *, integer *); static doublereal safmin; extern /* Subroutine */ int dlaset_(char *, integer *, integer *, doublereal *, doublereal *, doublereal *, integer *); static doublereal safmax; static char chtemp[1]; static logical ldumma[1]; extern /* Subroutine */ int dhgeqz_(char *, char *, char *, integer *, integer *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, doublereal *, doublereal *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, integer *), dtgevc_(char *, char *, logical *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, integer *, integer *, doublereal *, integer *), xerbla_(char *, integer *); static integer ijobvl, iright; static logical ilimit; extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *, ftnlen, ftnlen); static integer ijobvr; extern /* Subroutine */ int dorgqr_(integer *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, integer *); static doublereal onepls; static integer lwkmin, nb1, nb2, nb3; extern /* Subroutine */ int dormqr_(char *, char *, integer *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, doublereal *, integer *, integer *); static integer lwkopt; static logical lquery; static integer ihi, ilo; static doublereal eps; static logical ilv; #define a_ref(a_1,a_2) a[(a_2)*a_dim1 + a_1] #define b_ref(a_1,a_2) b[(a_2)*b_dim1 + a_1] #define vl_ref(a_1,a_2) vl[(a_2)*vl_dim1 + a_1] #define vr_ref(a_1,a_2) vr[(a_2)*vr_dim1 + a_1] a_dim1 = *lda; a_offset = 1 + a_dim1 * 1; a -= a_offset; b_dim1 = *ldb; b_offset = 1 + b_dim1 * 1; b -= b_offset; --alphar; --alphai; --beta; vl_dim1 = *ldvl; vl_offset = 1 + vl_dim1 * 1; vl -= vl_offset; vr_dim1 = *ldvr; vr_offset = 1 + vr_dim1 * 1; vr -= vr_offset; --work; /* Function Body */ if (lsame_(jobvl, "N")) { ijobvl = 1; ilvl = FALSE_; } else if (lsame_(jobvl, "V")) { ijobvl = 2; ilvl = TRUE_; } else { ijobvl = -1; ilvl = FALSE_; } if (lsame_(jobvr, "N")) { ijobvr = 1; ilvr = FALSE_; } else if (lsame_(jobvr, "V")) { ijobvr = 2; ilvr = TRUE_; } else { ijobvr = -1; ilvr = FALSE_; } ilv = ilvl || ilvr; /* Test the input arguments Computing MAX */ i__1 = *n << 3; lwkmin = max(i__1,1); lwkopt = lwkmin; work[1] = (doublereal) lwkopt; lquery = *lwork == -1; *info = 0; if (ijobvl <= 0) { *info = -1; } else if (ijobvr <= 0) { *info = -2; } else if (*n < 0) { *info = -3; } else if (*lda < max(1,*n)) { *info = -5; } else if (*ldb < max(1,*n)) { *info = -7; } else if (*ldvl < 1 || ilvl && *ldvl < *n) { *info = -12; } else if (*ldvr < 1 || ilvr && *ldvr < *n) { *info = -14; } else if (*lwork < lwkmin && ! lquery) { *info = -16; } if (*info == 0) { nb1 = ilaenv_(&c__1, "DGEQRF", " ", n, n, &c_n1, &c_n1, (ftnlen)6, ( ftnlen)1); nb2 = ilaenv_(&c__1, "DORMQR", " ", n, n, n, &c_n1, (ftnlen)6, ( ftnlen)1); nb3 = ilaenv_(&c__1, "DORGQR", " ", n, n, n, &c_n1, (ftnlen)6, ( ftnlen)1); /* Computing MAX */ i__1 = max(nb1,nb2); nb = max(i__1,nb3); /* Computing MAX */ i__1 = *n * 6, i__2 = *n * (nb + 1); lopt = (*n << 1) + max(i__1,i__2); work[1] = (doublereal) lopt; } if (*info != 0) { i__1 = -(*info); xerbla_("DGEGV ", &i__1); return 0; } else if (lquery) { return 0; } /* Quick return if possible */ if (*n == 0) { return 0; } /* Get machine constants */ eps = dlamch_("E") * dlamch_("B"); safmin = dlamch_("S"); safmin += safmin; safmax = 1. / safmin; onepls = eps * 4 + 1.; /* Scale A */ anrm = dlange_("M", n, n, &a[a_offset], lda, &work[1]); anrm1 = anrm; anrm2 = 1.; if (anrm < 1.) { if (safmax * anrm < 1.) { anrm1 = safmin; anrm2 = safmax * anrm; } } if (anrm > 0.) { dlascl_("G", &c_n1, &c_n1, &anrm, &c_b27, n, n, &a[a_offset], lda, & iinfo); if (iinfo != 0) { *info = *n + 10; return 0; } } /* Scale B */ bnrm = dlange_("M", n, n, &b[b_offset], ldb, &work[1]); bnrm1 = bnrm; bnrm2 = 1.; if (bnrm < 1.) { if (safmax * bnrm < 1.) { bnrm1 = safmin; bnrm2 = safmax * bnrm; } } if (bnrm > 0.) { dlascl_("G", &c_n1, &c_n1, &bnrm, &c_b27, n, n, &b[b_offset], ldb, & iinfo); if (iinfo != 0) { *info = *n + 10; return 0; } } /* Permute the matrix to make it more nearly triangular Workspace layout: (8*N words -- "work" requires 6*N words) left_permutation, right_permutation, work... */ ileft = 1; iright = *n + 1; iwork = iright + *n; dggbal_("P", n, &a[a_offset], lda, &b[b_offset], ldb, &ilo, &ihi, &work[ ileft], &work[iright], &work[iwork], &iinfo); if (iinfo != 0) { *info = *n + 1; goto L120; } /* Reduce B to triangular form, and initialize VL and/or VR Workspace layout: ("work..." must have at least N words) left_permutation, right_permutation, tau, work... */ irows = ihi + 1 - ilo; if (ilv) { icols = *n + 1 - ilo; } else { icols = irows; } itau = iwork; iwork = itau + irows; i__1 = *lwork + 1 - iwork; dgeqrf_(&irows, &icols, &b_ref(ilo, ilo), ldb, &work[itau], &work[iwork], &i__1, &iinfo); if (iinfo >= 0) { /* Computing MAX */ i__1 = lwkopt, i__2 = (integer) work[iwork] + iwork - 1; lwkopt = max(i__1,i__2); } if (iinfo != 0) { *info = *n + 2; goto L120; } i__1 = *lwork + 1 - iwork; dormqr_("L", "T", &irows, &icols, &irows, &b_ref(ilo, ilo), ldb, &work[ itau], &a_ref(ilo, ilo), lda, &work[iwork], &i__1, &iinfo); if (iinfo >= 0) { /* Computing MAX */ i__1 = lwkopt, i__2 = (integer) work[iwork] + iwork - 1; lwkopt = max(i__1,i__2); } if (iinfo != 0) { *info = *n + 3; goto L120; } if (ilvl) { dlaset_("Full", n, n, &c_b38, &c_b27, &vl[vl_offset], ldvl) ; i__1 = irows - 1; i__2 = irows - 1; dlacpy_("L", &i__1, &i__2, &b_ref(ilo + 1, ilo), ldb, &vl_ref(ilo + 1, ilo), ldvl); i__1 = *lwork + 1 - iwork; dorgqr_(&irows, &irows, &irows, &vl_ref(ilo, ilo), ldvl, &work[itau], &work[iwork], &i__1, &iinfo); if (iinfo >= 0) { /* Computing MAX */ i__1 = lwkopt, i__2 = (integer) work[iwork] + iwork - 1; lwkopt = max(i__1,i__2); } if (iinfo != 0) { *info = *n + 4; goto L120; } } if (ilvr) { dlaset_("Full", n, n, &c_b38, &c_b27, &vr[vr_offset], ldvr) ; } /* Reduce to generalized Hessenberg form */ if (ilv) { /* Eigenvectors requested -- work on whole matrix. */ dgghrd_(jobvl, jobvr, n, &ilo, &ihi, &a[a_offset], lda, &b[b_offset], ldb, &vl[vl_offset], ldvl, &vr[vr_offset], ldvr, &iinfo); } else { dgghrd_("N", "N", &irows, &c__1, &irows, &a_ref(ilo, ilo), lda, & b_ref(ilo, ilo), ldb, &vl[vl_offset], ldvl, &vr[vr_offset], ldvr, &iinfo); } if (iinfo != 0) { *info = *n + 5; goto L120; } /* Perform QZ algorithm Workspace layout: ("work..." must have at least 1 word) left_permutation, right_permutation, work... */ iwork = itau; if (ilv) { *(unsigned char *)chtemp = 'S'; } else { *(unsigned char *)chtemp = 'E'; } i__1 = *lwork + 1 - iwork; dhgeqz_(chtemp, jobvl, jobvr, n, &ilo, &ihi, &a[a_offset], lda, &b[ b_offset], ldb, &alphar[1], &alphai[1], &beta[1], &vl[vl_offset], ldvl, &vr[vr_offset], ldvr, &work[iwork], &i__1, &iinfo); if (iinfo >= 0) { /* Computing MAX */ i__1 = lwkopt, i__2 = (integer) work[iwork] + iwork - 1; lwkopt = max(i__1,i__2); } if (iinfo != 0) { if (iinfo > 0 && iinfo <= *n) { *info = iinfo; } else if (iinfo > *n && iinfo <= *n << 1) { *info = iinfo - *n; } else { *info = *n + 6; } goto L120; } if (ilv) { /* Compute Eigenvectors (DTGEVC requires 6*N words of workspace) */ if (ilvl) { if (ilvr) { *(unsigned char *)chtemp = 'B'; } else { *(unsigned char *)chtemp = 'L'; } } else { *(unsigned char *)chtemp = 'R'; } dtgevc_(chtemp, "B", ldumma, n, &a[a_offset], lda, &b[b_offset], ldb, &vl[vl_offset], ldvl, &vr[vr_offset], ldvr, n, &in, &work[ iwork], &iinfo); if (iinfo != 0) { *info = *n + 7; goto L120; } /* Undo balancing on VL and VR, rescale */ if (ilvl) { dggbak_("P", "L", n, &ilo, &ihi, &work[ileft], &work[iright], n, & vl[vl_offset], ldvl, &iinfo); if (iinfo != 0) { *info = *n + 8; goto L120; } i__1 = *n; for (jc = 1; jc <= i__1; ++jc) { if (alphai[jc] < 0.) { goto L50; } temp = 0.; if (alphai[jc] == 0.) { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { /* Computing MAX */ d__2 = temp, d__3 = (d__1 = vl_ref(jr, jc), abs(d__1)) ; temp = max(d__2,d__3); /* L10: */ } } else { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { /* Computing MAX */ d__3 = temp, d__4 = (d__1 = vl_ref(jr, jc), abs(d__1)) + (d__2 = vl_ref(jr, jc + 1), abs(d__2)); temp = max(d__3,d__4); /* L20: */ } } if (temp < safmin) { goto L50; } temp = 1. / temp; if (alphai[jc] == 0.) { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { vl_ref(jr, jc) = vl_ref(jr, jc) * temp; /* L30: */ } } else { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { vl_ref(jr, jc) = vl_ref(jr, jc) * temp; vl_ref(jr, jc + 1) = vl_ref(jr, jc + 1) * temp; /* L40: */ } } L50: ; } } if (ilvr) { dggbak_("P", "R", n, &ilo, &ihi, &work[ileft], &work[iright], n, & vr[vr_offset], ldvr, &iinfo); if (iinfo != 0) { *info = *n + 9; goto L120; } i__1 = *n; for (jc = 1; jc <= i__1; ++jc) { if (alphai[jc] < 0.) { goto L100; } temp = 0.; if (alphai[jc] == 0.) { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { /* Computing MAX */ d__2 = temp, d__3 = (d__1 = vr_ref(jr, jc), abs(d__1)) ; temp = max(d__2,d__3); /* L60: */ } } else { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { /* Computing MAX */ d__3 = temp, d__4 = (d__1 = vr_ref(jr, jc), abs(d__1)) + (d__2 = vr_ref(jr, jc + 1), abs(d__2)); temp = max(d__3,d__4); /* L70: */ } } if (temp < safmin) { goto L100; } temp = 1. / temp; if (alphai[jc] == 0.) { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { vr_ref(jr, jc) = vr_ref(jr, jc) * temp; /* L80: */ } } else { i__2 = *n; for (jr = 1; jr <= i__2; ++jr) { vr_ref(jr, jc) = vr_ref(jr, jc) * temp; vr_ref(jr, jc + 1) = vr_ref(jr, jc + 1) * temp; /* L90: */ } } L100: ; } } /* End of eigenvector calculation */ } /* Undo scaling in alpha, beta Note: this does not give the alpha and beta for the unscaled problem. Un-scaling is limited to avoid underflow in alpha and beta if they are significant. */ i__1 = *n; for (jc = 1; jc <= i__1; ++jc) { absar = (d__1 = alphar[jc], abs(d__1)); absai = (d__1 = alphai[jc], abs(d__1)); absb = (d__1 = beta[jc], abs(d__1)); salfar = anrm * alphar[jc]; salfai = anrm * alphai[jc]; sbeta = bnrm * beta[jc]; ilimit = FALSE_; scale = 1.; /* Check for significant underflow in ALPHAI Computing MAX */ d__1 = safmin, d__2 = eps * absar, d__1 = max(d__1,d__2), d__2 = eps * absb; if (abs(salfai) < safmin && absai >= max(d__1,d__2)) { ilimit = TRUE_; /* Computing MAX */ d__1 = onepls * safmin, d__2 = anrm2 * absai; scale = onepls * safmin / anrm1 / max(d__1,d__2); } else if (salfai == 0.) { /* If insignificant underflow in ALPHAI, then make the conjugate eigenvalue real. */ if (alphai[jc] < 0. && jc > 1) { alphai[jc - 1] = 0.; } else if (alphai[jc] > 0. && jc < *n) { alphai[jc + 1] = 0.; } } /* Check for significant underflow in ALPHAR Computing MAX */ d__1 = safmin, d__2 = eps * absai, d__1 = max(d__1,d__2), d__2 = eps * absb; if (abs(salfar) < safmin && absar >= max(d__1,d__2)) { ilimit = TRUE_; /* Computing MAX Computing MAX */ d__3 = onepls * safmin, d__4 = anrm2 * absar; d__1 = scale, d__2 = onepls * safmin / anrm1 / max(d__3,d__4); scale = max(d__1,d__2); } /* Check for significant underflow in BETA Computing MAX */ d__1 = safmin, d__2 = eps * absar, d__1 = max(d__1,d__2), d__2 = eps * absai; if (abs(sbeta) < safmin && absb >= max(d__1,d__2)) { ilimit = TRUE_; /* Computing MAX Computing MAX */ d__3 = onepls * safmin, d__4 = bnrm2 * absb; d__1 = scale, d__2 = onepls * safmin / bnrm1 / max(d__3,d__4); scale = max(d__1,d__2); } /* Check for possible overflow when limiting scaling */ if (ilimit) { /* Computing MAX */ d__1 = abs(salfar), d__2 = abs(salfai), d__1 = max(d__1,d__2), d__2 = abs(sbeta); temp = scale * safmin * max(d__1,d__2); if (temp > 1.) { scale /= temp; } if (scale < 1.) { ilimit = FALSE_; } } /* Recompute un-scaled ALPHAR, ALPHAI, BETA if necessary. */ if (ilimit) { salfar = scale * alphar[jc] * anrm; salfai = scale * alphai[jc] * anrm; sbeta = scale * beta[jc] * bnrm; } alphar[jc] = salfar; alphai[jc] = salfai; beta[jc] = sbeta; /* L110: */ } L120: work[1] = (doublereal) lwkopt; return 0; /* End of DGEGV */ } /* dgegv_ */ #undef vr_ref #undef vl_ref #undef b_ref #undef a_ref