/* sgsvj1.f -- translated by f2c (version 20061008). You must link the resulting object file with libf2c: on Microsoft Windows system, link with libf2c.lib; on Linux or Unix systems, link with .../path/to/libf2c.a -lm or, if you install libf2c.a in a standard place, with -lf2c -lm -- in that order, at the end of the command line, as in cc *.o -lf2c -lm Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., http://www.netlib.org/f2c/libf2c.zip */ #include "f2c.h" #include "blaswrap.h" /* Table of constant values */ static integer c__1 = 1; static integer c__0 = 0; static real c_b35 = 1.f; /* Subroutine */ int sgsvj1_(char *jobv, integer *m, integer *n, integer *n1, real *a, integer *lda, real *d__, real *sva, integer *mv, real *v, integer *ldv, real *eps, real *sfmin, real *tol, integer *nsweep, real *work, integer *lwork, integer *info) { /* System generated locals */ integer a_dim1, a_offset, v_dim1, v_offset, i__1, i__2, i__3, i__4, i__5, i__6; real r__1, r__2; /* Builtin functions */ double sqrt(doublereal), r_sign(real *, real *); /* Local variables */ real bigtheta; integer pskipped, i__, p, q; real t, rootsfmin, cs, sn; integer jbc; real big; integer kbl, igl, ibr, jgl, mvl, nblc; real aapp, aapq, aaqq; integer nblr, ierr; extern doublereal sdot_(integer *, real *, integer *, real *, integer *); real aapp0, temp1; extern doublereal snrm2_(integer *, real *, integer *); real large, apoaq, aqoap; extern logical lsame_(char *, char *); real theta, small, fastr[5]; logical applv, rsvec; extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, integer *); logical rotok; extern /* Subroutine */ int sswap_(integer *, real *, integer *, real *, integer *), saxpy_(integer *, real *, real *, integer *, real *, integer *), srotm_(integer *, real *, integer *, real *, integer * , real *), xerbla_(char *, integer *); integer ijblsk, swband; extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, real *, integer *, integer *, real *, integer *, integer *); extern integer isamax_(integer *, real *, integer *); integer blskip; real mxaapq, thsign; extern /* Subroutine */ int slassq_(integer *, real *, integer *, real *, real *); real mxsinj; integer emptsw, notrot, iswrot; real rootbig, rooteps; integer rowskip; real roottol; /* -- LAPACK routine (version 3.2) -- */ /* -- Contributed by Zlatko Drmac of the University of Zagreb and -- */ /* -- Kresimir Veselic of the Fernuniversitaet Hagen -- */ /* -- November 2008 -- */ /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */ /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */ /* This routine is also part of SIGMA (version 1.23, October 23. 2008.) */ /* SIGMA is a library of algorithms for highly accurate algorithms for */ /* computation of SVD, PSVD, QSVD, (H,K)-SVD, and for solution of the */ /* eigenvalue problems Hx = lambda M x, H M x = lambda x with H, M > 0. */ /* -#- Scalar Arguments -#- */ /* -#- Array Arguments -#- */ /* .. */ /* Purpose */ /* ~~~~~~~ */ /* SGSVJ1 is called from SGESVJ as a pre-processor and that is its main */ /* purpose. It applies Jacobi rotations in the same way as SGESVJ does, but */ /* it targets only particular pivots and it does not check convergence */ /* (stopping criterion). Few tunning parameters (marked by [TP]) are */ /* available for the implementer. */ /* Further details */ /* ~~~~~~~~~~~~~~~ */ /* SGSVJ1 applies few sweeps of Jacobi rotations in the column space of */ /* the input M-by-N matrix A. The pivot pairs are taken from the (1,2) */ /* off-diagonal block in the corresponding N-by-N Gram matrix A^T * A. The */ /* block-entries (tiles) of the (1,2) off-diagonal block are marked by the */ /* [x]'s in the following scheme: */ /* | * * * [x] [x] [x]| */ /* | * * * [x] [x] [x]| Row-cycling in the nblr-by-nblc [x] blocks. */ /* | * * * [x] [x] [x]| Row-cyclic pivoting inside each [x] block. */ /* |[x] [x] [x] * * * | */ /* |[x] [x] [x] * * * | */ /* |[x] [x] [x] * * * | */ /* In terms of the columns of A, the first N1 columns are rotated 'against' */ /* the remaining N-N1 columns, trying to increase the angle between the */ /* corresponding subspaces. The off-diagonal block is N1-by(N-N1) and it is */ /* tiled using quadratic tiles of side KBL. Here, KBL is a tunning parmeter. */ /* The number of sweeps is given in NSWEEP and the orthogonality threshold */ /* is given in TOL. */ /* Contributors */ /* ~~~~~~~~~~~~ */ /* Zlatko Drmac (Zagreb, Croatia) and Kresimir Veselic (Hagen, Germany) */ /* Arguments */ /* ~~~~~~~~~ */ /* JOBV (input) CHARACTER*1 */ /* Specifies whether the output from this procedure is used */ /* to compute the matrix V: */ /* = 'V': the product of the Jacobi rotations is accumulated */ /* by postmulyiplying the N-by-N array V. */ /* (See the description of V.) */ /* = 'A': the product of the Jacobi rotations is accumulated */ /* by postmulyiplying the MV-by-N array V. */ /* (See the descriptions of MV and V.) */ /* = 'N': the Jacobi rotations are not accumulated. */ /* M (input) INTEGER */ /* The number of rows of the input matrix A. M >= 0. */ /* N (input) INTEGER */ /* The number of columns of the input matrix A. */ /* M >= N >= 0. */ /* N1 (input) INTEGER */ /* N1 specifies the 2 x 2 block partition, the first N1 columns are */ /* rotated 'against' the remaining N-N1 columns of A. */ /* A (input/output) REAL array, dimension (LDA,N) */ /* On entry, M-by-N matrix A, such that A*diag(D) represents */ /* the input matrix. */ /* On exit, */ /* A_onexit * D_onexit represents the input matrix A*diag(D) */ /* post-multiplied by a sequence of Jacobi rotations, where the */ /* rotation threshold and the total number of sweeps are given in */ /* TOL and NSWEEP, respectively. */ /* (See the descriptions of N1, D, TOL and NSWEEP.) */ /* LDA (input) INTEGER */ /* The leading dimension of the array A. LDA >= max(1,M). */ /* D (input/workspace/output) REAL array, dimension (N) */ /* The array D accumulates the scaling factors from the fast scaled */ /* Jacobi rotations. */ /* On entry, A*diag(D) represents the input matrix. */ /* On exit, A_onexit*diag(D_onexit) represents the input matrix */ /* post-multiplied by a sequence of Jacobi rotations, where the */ /* rotation threshold and the total number of sweeps are given in */ /* TOL and NSWEEP, respectively. */ /* (See the descriptions of N1, A, TOL and NSWEEP.) */ /* SVA (input/workspace/output) REAL array, dimension (N) */ /* On entry, SVA contains the Euclidean norms of the columns of */ /* the matrix A*diag(D). */ /* On exit, SVA contains the Euclidean norms of the columns of */ /* the matrix onexit*diag(D_onexit). */ /* MV (input) INTEGER */ /* If JOBV .EQ. 'A', then MV rows of V are post-multipled by a */ /* sequence of Jacobi rotations. */ /* If JOBV = 'N', then MV is not referenced. */ /* V (input/output) REAL array, dimension (LDV,N) */ /* If JOBV .EQ. 'V' then N rows of V are post-multipled by a */ /* sequence of Jacobi rotations. */ /* If JOBV .EQ. 'A' then MV rows of V are post-multipled by a */ /* sequence of Jacobi rotations. */ /* If JOBV = 'N', then V is not referenced. */ /* LDV (input) INTEGER */ /* The leading dimension of the array V, LDV >= 1. */ /* If JOBV = 'V', LDV .GE. N. */ /* If JOBV = 'A', LDV .GE. MV. */ /* EPS (input) INTEGER */ /* EPS = SLAMCH('Epsilon') */ /* SFMIN (input) INTEGER */ /* SFMIN = SLAMCH('Safe Minimum') */ /* TOL (input) REAL */ /* TOL is the threshold for Jacobi rotations. For a pair */ /* A(:,p), A(:,q) of pivot columns, the Jacobi rotation is */ /* applied only if ABS(COS(angle(A(:,p),A(:,q)))) .GT. TOL. */ /* NSWEEP (input) INTEGER */ /* NSWEEP is the number of sweeps of Jacobi rotations to be */ /* performed. */ /* WORK (workspace) REAL array, dimension LWORK. */ /* LWORK (input) INTEGER */ /* LWORK is the dimension of WORK. LWORK .GE. M. */ /* INFO (output) INTEGER */ /* = 0 : successful exit. */ /* < 0 : if INFO = -i, then the i-th argument had an illegal value */ /* -#- Local Parameters -#- */ /* -#- Local Scalars -#- */ /* Local Arrays */ /* Intrinsic Functions */ /* External Functions */ /* External Subroutines */ /* Parameter adjustments */ --sva; --d__; a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; v_dim1 = *ldv; v_offset = 1 + v_dim1; v -= v_offset; --work; /* Function Body */ applv = lsame_(jobv, "A"); rsvec = lsame_(jobv, "V"); if (! (rsvec || applv || lsame_(jobv, "N"))) { *info = -1; } else if (*m < 0) { *info = -2; } else if (*n < 0 || *n > *m) { *info = -3; } else if (*n1 < 0) { *info = -4; } else if (*lda < *m) { *info = -6; } else if (*mv < 0) { *info = -9; } else if (*ldv < *m) { *info = -11; } else if (*tol <= *eps) { *info = -14; } else if (*nsweep < 0) { *info = -15; } else if (*lwork < *m) { *info = -17; } else { *info = 0; } /* #:( */ if (*info != 0) { i__1 = -(*info); xerbla_("SGSVJ1", &i__1); return 0; } if (rsvec) { mvl = *n; } else if (applv) { mvl = *mv; } rsvec = rsvec || applv; rooteps = sqrt(*eps); rootsfmin = sqrt(*sfmin); small = *sfmin / *eps; big = 1.f / *sfmin; rootbig = 1.f / rootsfmin; large = big / sqrt((real) (*m * *n)); bigtheta = 1.f / rooteps; roottol = sqrt(*tol); /* -#- Initialize the right singular vector matrix -#- */ /* RSVEC = LSAME( JOBV, 'Y' ) */ emptsw = *n1 * (*n - *n1); notrot = 0; fastr[0] = 0.f; /* -#- Row-cyclic pivot strategy with de Rijk's pivoting -#- */ kbl = min(8,*n); nblr = *n1 / kbl; if (nblr * kbl != *n1) { ++nblr; } /* .. the tiling is nblr-by-nblc [tiles] */ nblc = (*n - *n1) / kbl; if (nblc * kbl != *n - *n1) { ++nblc; } /* Computing 2nd power */ i__1 = kbl; blskip = i__1 * i__1 + 1; /* [TP] BLKSKIP is a tuning parameter that depends on SWBAND and KBL. */ rowskip = min(5,kbl); /* [TP] ROWSKIP is a tuning parameter. */ swband = 0; /* [TP] SWBAND is a tuning parameter. It is meaningful and effective */ /* if SGESVJ is used as a computational routine in the preconditioned */ /* Jacobi SVD algorithm SGESVJ. */ /* | * * * [x] [x] [x]| */ /* | * * * [x] [x] [x]| Row-cycling in the nblr-by-nblc [x] blocks. */ /* | * * * [x] [x] [x]| Row-cyclic pivoting inside each [x] block. */ /* |[x] [x] [x] * * * | */ /* |[x] [x] [x] * * * | */ /* |[x] [x] [x] * * * | */ i__1 = *nsweep; for (i__ = 1; i__ <= i__1; ++i__) { /* .. go go go ... */ mxaapq = 0.f; mxsinj = 0.f; iswrot = 0; notrot = 0; pskipped = 0; i__2 = nblr; for (ibr = 1; ibr <= i__2; ++ibr) { igl = (ibr - 1) * kbl + 1; /* ........................................................ */ /* ... go to the off diagonal blocks */ igl = (ibr - 1) * kbl + 1; i__3 = nblc; for (jbc = 1; jbc <= i__3; ++jbc) { jgl = *n1 + (jbc - 1) * kbl + 1; /* doing the block at ( ibr, jbc ) */ ijblsk = 0; /* Computing MIN */ i__5 = igl + kbl - 1; i__4 = min(i__5,*n1); for (p = igl; p <= i__4; ++p) { aapp = sva[p]; if (aapp > 0.f) { pskipped = 0; /* Computing MIN */ i__6 = jgl + kbl - 1; i__5 = min(i__6,*n); for (q = jgl; q <= i__5; ++q) { aaqq = sva[q]; if (aaqq > 0.f) { aapp0 = aapp; /* -#- M x 2 Jacobi SVD -#- */ /* -#- Safe Gram matrix computation -#- */ if (aaqq >= 1.f) { if (aapp >= aaqq) { rotok = small * aapp <= aaqq; } else { rotok = small * aaqq <= aapp; } if (aapp < big / aaqq) { aapq = sdot_(m, &a[p * a_dim1 + 1], & c__1, &a[q * a_dim1 + 1], & c__1) * d__[p] * d__[q] / aaqq / aapp; } else { scopy_(m, &a[p * a_dim1 + 1], &c__1, & work[1], &c__1); slascl_("G", &c__0, &c__0, &aapp, & d__[p], m, &c__1, &work[1], lda, &ierr); aapq = sdot_(m, &work[1], &c__1, &a[q * a_dim1 + 1], &c__1) * d__[q] / aaqq; } } else { if (aapp >= aaqq) { rotok = aapp <= aaqq / small; } else { rotok = aaqq <= aapp / small; } if (aapp > small / aaqq) { aapq = sdot_(m, &a[p * a_dim1 + 1], & c__1, &a[q * a_dim1 + 1], & c__1) * d__[p] * d__[q] / aaqq / aapp; } else { scopy_(m, &a[q * a_dim1 + 1], &c__1, & work[1], &c__1); slascl_("G", &c__0, &c__0, &aaqq, & d__[q], m, &c__1, &work[1], lda, &ierr); aapq = sdot_(m, &work[1], &c__1, &a[p * a_dim1 + 1], &c__1) * d__[p] / aapp; } } /* Computing MAX */ r__1 = mxaapq, r__2 = dabs(aapq); mxaapq = dmax(r__1,r__2); /* TO rotate or NOT to rotate, THAT is the question ... */ if (dabs(aapq) > *tol) { notrot = 0; /* ROTATED = ROTATED + 1 */ pskipped = 0; ++iswrot; if (rotok) { aqoap = aaqq / aapp; apoaq = aapp / aaqq; theta = (r__1 = aqoap - apoaq, dabs( r__1)) * -.5f / aapq; if (aaqq > aapp0) { theta = -theta; } if (dabs(theta) > bigtheta) { t = .5f / theta; fastr[2] = t * d__[p] / d__[q]; fastr[3] = -t * d__[q] / d__[p]; srotm_(m, &a[p * a_dim1 + 1], & c__1, &a[q * a_dim1 + 1], &c__1, fastr); if (rsvec) { srotm_(&mvl, &v[p * v_dim1 + 1], &c__1, &v[q * v_dim1 + 1], &c__1, fastr); } /* Computing MAX */ r__1 = 0.f, r__2 = t * apoaq * aapq + 1.f; sva[q] = aaqq * sqrt((dmax(r__1, r__2))); /* Computing MAX */ r__1 = 0.f, r__2 = 1.f - t * aqoap * aapq; aapp *= sqrt((dmax(r__1,r__2))); /* Computing MAX */ r__1 = mxsinj, r__2 = dabs(t); mxsinj = dmax(r__1,r__2); } else { /* .. choose correct signum for THETA and rotate */ thsign = -r_sign(&c_b35, &aapq); if (aaqq > aapp0) { thsign = -thsign; } t = 1.f / (theta + thsign * sqrt( theta * theta + 1.f)); cs = sqrt(1.f / (t * t + 1.f)); sn = t * cs; /* Computing MAX */ r__1 = mxsinj, r__2 = dabs(sn); mxsinj = dmax(r__1,r__2); /* Computing MAX */ r__1 = 0.f, r__2 = t * apoaq * aapq + 1.f; sva[q] = aaqq * sqrt((dmax(r__1, r__2))); aapp *= sqrt(1.f - t * aqoap * aapq); apoaq = d__[p] / d__[q]; aqoap = d__[q] / d__[p]; if (d__[p] >= 1.f) { if (d__[q] >= 1.f) { fastr[2] = t * apoaq; fastr[3] = -t * aqoap; d__[p] *= cs; d__[q] *= cs; srotm_(m, &a[p * a_dim1 + 1], &c__1, &a[q * a_dim1 + 1], &c__1, fastr); if (rsvec) { srotm_(&mvl, &v[p * v_dim1 + 1], &c__1, &v[ q * v_dim1 + 1], &c__1, fastr); } } else { r__1 = -t * aqoap; saxpy_(m, &r__1, &a[q * a_dim1 + 1], &c__1, &a[ p * a_dim1 + 1], &c__1); r__1 = cs * sn * apoaq; saxpy_(m, &r__1, &a[p * a_dim1 + 1], &c__1, &a[ q * a_dim1 + 1], &c__1); if (rsvec) { r__1 = -t * aqoap; saxpy_(&mvl, &r__1, &v[q * v_dim1 + 1], & c__1, &v[p * v_dim1 + 1], &c__1); r__1 = cs * sn * apoaq; saxpy_(&mvl, &r__1, &v[p * v_dim1 + 1], & c__1, &v[q * v_dim1 + 1], &c__1); } d__[p] *= cs; d__[q] /= cs; } } else { if (d__[q] >= 1.f) { r__1 = t * apoaq; saxpy_(m, &r__1, &a[p * a_dim1 + 1], &c__1, &a[ q * a_dim1 + 1], &c__1); r__1 = -cs * sn * aqoap; saxpy_(m, &r__1, &a[q * a_dim1 + 1], &c__1, &a[ p * a_dim1 + 1], &c__1); if (rsvec) { r__1 = t * apoaq; saxpy_(&mvl, &r__1, &v[p * v_dim1 + 1], & c__1, &v[q * v_dim1 + 1], &c__1); r__1 = -cs * sn * aqoap; saxpy_(&mvl, &r__1, &v[q * v_dim1 + 1], & c__1, &v[p * v_dim1 + 1], &c__1); } d__[p] /= cs; d__[q] *= cs; } else { if (d__[p] >= d__[q]) { r__1 = -t * aqoap; saxpy_(m, &r__1, &a[q * a_dim1 + 1], &c__1, &a[p * a_dim1 + 1], &c__1); r__1 = cs * sn * apoaq; saxpy_(m, &r__1, &a[p * a_dim1 + 1], &c__1, &a[q * a_dim1 + 1], &c__1); d__[p] *= cs; d__[q] /= cs; if (rsvec) { r__1 = -t * aqoap; saxpy_(&mvl, &r__1, &v[q * v_dim1 + 1], &c__1, &v[p * v_dim1 + 1], & c__1); r__1 = cs * sn * apoaq; saxpy_(&mvl, &r__1, &v[p * v_dim1 + 1], &c__1, &v[q * v_dim1 + 1], & c__1); } } else { r__1 = t * apoaq; saxpy_(m, &r__1, &a[p * a_dim1 + 1], &c__1, &a[q * a_dim1 + 1], &c__1); r__1 = -cs * sn * aqoap; saxpy_(m, &r__1, &a[q * a_dim1 + 1], &c__1, &a[p * a_dim1 + 1], &c__1); d__[p] /= cs; d__[q] *= cs; if (rsvec) { r__1 = t * apoaq; saxpy_(&mvl, &r__1, &v[p * v_dim1 + 1], &c__1, &v[q * v_dim1 + 1], & c__1); r__1 = -cs * sn * aqoap; saxpy_(&mvl, &r__1, &v[q * v_dim1 + 1], &c__1, &v[p * v_dim1 + 1], & c__1); } } } } } } else { if (aapp > aaqq) { scopy_(m, &a[p * a_dim1 + 1], & c__1, &work[1], &c__1); slascl_("G", &c__0, &c__0, &aapp, &c_b35, m, &c__1, &work[1] , lda, &ierr); slascl_("G", &c__0, &c__0, &aaqq, &c_b35, m, &c__1, &a[q * a_dim1 + 1], lda, &ierr); temp1 = -aapq * d__[p] / d__[q]; saxpy_(m, &temp1, &work[1], &c__1, &a[q * a_dim1 + 1], & c__1); slascl_("G", &c__0, &c__0, &c_b35, &aaqq, m, &c__1, &a[q * a_dim1 + 1], lda, &ierr); /* Computing MAX */ r__1 = 0.f, r__2 = 1.f - aapq * aapq; sva[q] = aaqq * sqrt((dmax(r__1, r__2))); mxsinj = dmax(mxsinj,*sfmin); } else { scopy_(m, &a[q * a_dim1 + 1], & c__1, &work[1], &c__1); slascl_("G", &c__0, &c__0, &aaqq, &c_b35, m, &c__1, &work[1] , lda, &ierr); slascl_("G", &c__0, &c__0, &aapp, &c_b35, m, &c__1, &a[p * a_dim1 + 1], lda, &ierr); temp1 = -aapq * d__[q] / d__[p]; saxpy_(m, &temp1, &work[1], &c__1, &a[p * a_dim1 + 1], & c__1); slascl_("G", &c__0, &c__0, &c_b35, &aapp, m, &c__1, &a[p * a_dim1 + 1], lda, &ierr); /* Computing MAX */ r__1 = 0.f, r__2 = 1.f - aapq * aapq; sva[p] = aapp * sqrt((dmax(r__1, r__2))); mxsinj = dmax(mxsinj,*sfmin); } } /* END IF ROTOK THEN ... ELSE */ /* In the case of cancellation in updating SVA(q) */ /* .. recompute SVA(q) */ /* Computing 2nd power */ r__1 = sva[q] / aaqq; if (r__1 * r__1 <= rooteps) { if (aaqq < rootbig && aaqq > rootsfmin) { sva[q] = snrm2_(m, &a[q * a_dim1 + 1], &c__1) * d__[q]; } else { t = 0.f; aaqq = 0.f; slassq_(m, &a[q * a_dim1 + 1], & c__1, &t, &aaqq); sva[q] = t * sqrt(aaqq) * d__[q]; } } /* Computing 2nd power */ r__1 = aapp / aapp0; if (r__1 * r__1 <= rooteps) { if (aapp < rootbig && aapp > rootsfmin) { aapp = snrm2_(m, &a[p * a_dim1 + 1], &c__1) * d__[p]; } else { t = 0.f; aapp = 0.f; slassq_(m, &a[p * a_dim1 + 1], & c__1, &t, &aapp); aapp = t * sqrt(aapp) * d__[p]; } sva[p] = aapp; } /* end of OK rotation */ } else { ++notrot; /* SKIPPED = SKIPPED + 1 */ ++pskipped; ++ijblsk; } } else { ++notrot; ++pskipped; ++ijblsk; } /* IF ( NOTROT .GE. EMPTSW ) GO TO 2011 */ if (i__ <= swband && ijblsk >= blskip) { sva[p] = aapp; notrot = 0; goto L2011; } if (i__ <= swband && pskipped > rowskip) { aapp = -aapp; notrot = 0; goto L2203; } /* L2200: */ } /* end of the q-loop */ L2203: sva[p] = aapp; } else { if (aapp == 0.f) { /* Computing MIN */ i__5 = jgl + kbl - 1; notrot = notrot + min(i__5,*n) - jgl + 1; } if (aapp < 0.f) { notrot = 0; } /* ** IF ( NOTROT .GE. EMPTSW ) GO TO 2011 */ } /* L2100: */ } /* end of the p-loop */ /* L2010: */ } /* end of the jbc-loop */ L2011: /* 2011 bailed out of the jbc-loop */ /* Computing MIN */ i__4 = igl + kbl - 1; i__3 = min(i__4,*n); for (p = igl; p <= i__3; ++p) { sva[p] = (r__1 = sva[p], dabs(r__1)); /* L2012: */ } /* ** IF ( NOTROT .GE. EMPTSW ) GO TO 1994 */ /* L2000: */ } /* 2000 :: end of the ibr-loop */ /* .. update SVA(N) */ if (sva[*n] < rootbig && sva[*n] > rootsfmin) { sva[*n] = snrm2_(m, &a[*n * a_dim1 + 1], &c__1) * d__[*n]; } else { t = 0.f; aapp = 0.f; slassq_(m, &a[*n * a_dim1 + 1], &c__1, &t, &aapp); sva[*n] = t * sqrt(aapp) * d__[*n]; } /* Additional steering devices */ if (i__ < swband && (mxaapq <= roottol || iswrot <= *n)) { swband = i__; } if (i__ > swband + 1 && mxaapq < (real) (*n) * *tol && (real) (*n) * mxaapq * mxsinj < *tol) { goto L1994; } if (notrot >= emptsw) { goto L1994; } /* L1993: */ } /* end i=1:NSWEEP loop */ /* #:) Reaching this point means that the procedure has completed the given */ /* number of sweeps. */ *info = *nsweep - 1; goto L1995; L1994: /* #:) Reaching this point means that during the i-th sweep all pivots were */ /* below the given threshold, causing early exit. */ *info = 0; /* #:) INFO = 0 confirms successful iterations. */ L1995: /* Sort the vector D */ i__1 = *n - 1; for (p = 1; p <= i__1; ++p) { i__2 = *n - p + 1; q = isamax_(&i__2, &sva[p], &c__1) + p - 1; if (p != q) { temp1 = sva[p]; sva[p] = sva[q]; sva[q] = temp1; temp1 = d__[p]; d__[p] = d__[q]; d__[q] = temp1; sswap_(m, &a[p * a_dim1 + 1], &c__1, &a[q * a_dim1 + 1], &c__1); if (rsvec) { sswap_(&mvl, &v[p * v_dim1 + 1], &c__1, &v[q * v_dim1 + 1], & c__1); } } /* L5991: */ } return 0; /* .. */ /* .. END OF SGSVJ1 */ /* .. */ } /* sgsvj1_ */