/* slasd6.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 "clapack.h" /* Table of constant values */ static integer c__0 = 0; static real c_b7 = 1.f; static integer c__1 = 1; static integer c_n1 = -1; /* Subroutine */ int slasd6_(integer *icompq, integer *nl, integer *nr, integer *sqre, real *d__, real *vf, real *vl, real *alpha, real *beta, integer *idxq, integer *perm, integer *givptr, integer *givcol, integer *ldgcol, real *givnum, integer *ldgnum, real *poles, real * difl, real *difr, real *z__, integer *k, real *c__, real *s, real * work, integer *iwork, integer *info) { /* System generated locals */ integer givcol_dim1, givcol_offset, givnum_dim1, givnum_offset, poles_dim1, poles_offset, i__1; real r__1, r__2; /* Local variables */ integer i__, m, n, n1, n2, iw, idx, idxc, idxp, ivfw, ivlw; extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, integer *), slasd7_(integer *, integer *, integer *, integer *, integer *, real *, real *, real *, real *, real *, real *, real *, real *, real *, real *, integer *, integer *, integer *, integer *, integer *, integer *, integer *, real *, integer *, real *, real *, integer *), slasd8_(integer *, integer *, real *, real *, real *, real *, real *, real *, integer *, real *, real *, integer *); integer isigma; extern /* Subroutine */ int xerbla_(char *, integer *), slascl_( char *, integer *, integer *, real *, real *, integer *, integer * , real *, integer *, integer *), slamrg_(integer *, integer *, real *, integer *, integer *, integer *); real orgnrm; /* -- LAPACK auxiliary routine (version 3.2) -- */ /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ /* November 2006 */ /* .. Scalar Arguments .. */ /* .. */ /* .. Array Arguments .. */ /* .. */ /* Purpose */ /* ======= */ /* SLASD6 computes the SVD of an updated upper bidiagonal matrix B */ /* obtained by merging two smaller ones by appending a row. This */ /* routine is used only for the problem which requires all singular */ /* values and optionally singular vector matrices in factored form. */ /* B is an N-by-M matrix with N = NL + NR + 1 and M = N + SQRE. */ /* A related subroutine, SLASD1, handles the case in which all singular */ /* values and singular vectors of the bidiagonal matrix are desired. */ /* SLASD6 computes the SVD as follows: */ /* ( D1(in) 0 0 0 ) */ /* B = U(in) * ( Z1' a Z2' b ) * VT(in) */ /* ( 0 0 D2(in) 0 ) */ /* = U(out) * ( D(out) 0) * VT(out) */ /* where Z' = (Z1' a Z2' b) = u' VT', and u is a vector of dimension M */ /* with ALPHA and BETA in the NL+1 and NL+2 th entries and zeros */ /* elsewhere; and the entry b is empty if SQRE = 0. */ /* The singular values of B can be computed using D1, D2, the first */ /* components of all the right singular vectors of the lower block, and */ /* the last components of all the right singular vectors of the upper */ /* block. These components are stored and updated in VF and VL, */ /* respectively, in SLASD6. Hence U and VT are not explicitly */ /* referenced. */ /* The singular values are stored in D. The algorithm consists of two */ /* stages: */ /* The first stage consists of deflating the size of the problem */ /* when there are multiple singular values or if there is a zero */ /* in the Z vector. For each such occurence the dimension of the */ /* secular equation problem is reduced by one. This stage is */ /* performed by the routine SLASD7. */ /* The second stage consists of calculating the updated */ /* singular values. This is done by finding the roots of the */ /* secular equation via the routine SLASD4 (as called by SLASD8). */ /* This routine also updates VF and VL and computes the distances */ /* between the updated singular values and the old singular */ /* values. */ /* SLASD6 is called from SLASDA. */ /* Arguments */ /* ========= */ /* ICOMPQ (input) INTEGER */ /* Specifies whether singular vectors are to be computed in */ /* factored form: */ /* = 0: Compute singular values only. */ /* = 1: Compute singular vectors in factored form as well. */ /* NL (input) INTEGER */ /* The row dimension of the upper block. NL >= 1. */ /* NR (input) INTEGER */ /* The row dimension of the lower block. NR >= 1. */ /* SQRE (input) INTEGER */ /* = 0: the lower block is an NR-by-NR square matrix. */ /* = 1: the lower block is an NR-by-(NR+1) rectangular matrix. */ /* The bidiagonal matrix has row dimension N = NL + NR + 1, */ /* and column dimension M = N + SQRE. */ /* D (input/output) REAL array, dimension (NL+NR+1). */ /* On entry D(1:NL,1:NL) contains the singular values of the */ /* upper block, and D(NL+2:N) contains the singular values */ /* of the lower block. On exit D(1:N) contains the singular */ /* values of the modified matrix. */ /* VF (input/output) REAL array, dimension (M) */ /* On entry, VF(1:NL+1) contains the first components of all */ /* right singular vectors of the upper block; and VF(NL+2:M) */ /* contains the first components of all right singular vectors */ /* of the lower block. On exit, VF contains the first components */ /* of all right singular vectors of the bidiagonal matrix. */ /* VL (input/output) REAL array, dimension (M) */ /* On entry, VL(1:NL+1) contains the last components of all */ /* right singular vectors of the upper block; and VL(NL+2:M) */ /* contains the last components of all right singular vectors of */ /* the lower block. On exit, VL contains the last components of */ /* all right singular vectors of the bidiagonal matrix. */ /* ALPHA (input/output) REAL */ /* Contains the diagonal element associated with the added row. */ /* BETA (input/output) REAL */ /* Contains the off-diagonal element associated with the added */ /* row. */ /* IDXQ (output) INTEGER array, dimension (N) */ /* This contains the permutation which will reintegrate the */ /* subproblem just solved back into sorted order, i.e. */ /* D( IDXQ( I = 1, N ) ) will be in ascending order. */ /* PERM (output) INTEGER array, dimension ( N ) */ /* The permutations (from deflation and sorting) to be applied */ /* to each block. Not referenced if ICOMPQ = 0. */ /* GIVPTR (output) INTEGER */ /* The number of Givens rotations which took place in this */ /* subproblem. Not referenced if ICOMPQ = 0. */ /* GIVCOL (output) INTEGER array, dimension ( LDGCOL, 2 ) */ /* Each pair of numbers indicates a pair of columns to take place */ /* in a Givens rotation. Not referenced if ICOMPQ = 0. */ /* LDGCOL (input) INTEGER */ /* leading dimension of GIVCOL, must be at least N. */ /* GIVNUM (output) REAL array, dimension ( LDGNUM, 2 ) */ /* Each number indicates the C or S value to be used in the */ /* corresponding Givens rotation. Not referenced if ICOMPQ = 0. */ /* LDGNUM (input) INTEGER */ /* The leading dimension of GIVNUM and POLES, must be at least N. */ /* POLES (output) REAL array, dimension ( LDGNUM, 2 ) */ /* On exit, POLES(1,*) is an array containing the new singular */ /* values obtained from solving the secular equation, and */ /* POLES(2,*) is an array containing the poles in the secular */ /* equation. Not referenced if ICOMPQ = 0. */ /* DIFL (output) REAL array, dimension ( N ) */ /* On exit, DIFL(I) is the distance between I-th updated */ /* (undeflated) singular value and the I-th (undeflated) old */ /* singular value. */ /* DIFR (output) REAL array, */ /* dimension ( LDGNUM, 2 ) if ICOMPQ = 1 and */ /* dimension ( N ) if ICOMPQ = 0. */ /* On exit, DIFR(I, 1) is the distance between I-th updated */ /* (undeflated) singular value and the I+1-th (undeflated) old */ /* singular value. */ /* If ICOMPQ = 1, DIFR(1:K,2) is an array containing the */ /* normalizing factors for the right singular vector matrix. */ /* See SLASD8 for details on DIFL and DIFR. */ /* Z (output) REAL array, dimension ( M ) */ /* The first elements of this array contain the components */ /* of the deflation-adjusted updating row vector. */ /* K (output) INTEGER */ /* Contains the dimension of the non-deflated matrix, */ /* This is the order of the related secular equation. 1 <= K <=N. */ /* C (output) REAL */ /* C contains garbage if SQRE =0 and the C-value of a Givens */ /* rotation related to the right null space if SQRE = 1. */ /* S (output) REAL */ /* S contains garbage if SQRE =0 and the S-value of a Givens */ /* rotation related to the right null space if SQRE = 1. */ /* WORK (workspace) REAL array, dimension ( 4 * M ) */ /* IWORK (workspace) INTEGER array, dimension ( 3 * N ) */ /* INFO (output) INTEGER */ /* = 0: successful exit. */ /* < 0: if INFO = -i, the i-th argument had an illegal value. */ /* > 0: if INFO = 1, an singular value did not converge */ /* Further Details */ /* =============== */ /* Based on contributions by */ /* Ming Gu and Huan Ren, Computer Science Division, University of */ /* California at Berkeley, USA */ /* ===================================================================== */ /* .. Parameters .. */ /* .. */ /* .. Local Scalars .. */ /* .. */ /* .. External Subroutines .. */ /* .. */ /* .. Intrinsic Functions .. */ /* .. */ /* .. Executable Statements .. */ /* Test the input parameters. */ /* Parameter adjustments */ --d__; --vf; --vl; --idxq; --perm; givcol_dim1 = *ldgcol; givcol_offset = 1 + givcol_dim1; givcol -= givcol_offset; poles_dim1 = *ldgnum; poles_offset = 1 + poles_dim1; poles -= poles_offset; givnum_dim1 = *ldgnum; givnum_offset = 1 + givnum_dim1; givnum -= givnum_offset; --difl; --difr; --z__; --work; --iwork; /* Function Body */ *info = 0; n = *nl + *nr + 1; m = n + *sqre; if (*icompq < 0 || *icompq > 1) { *info = -1; } else if (*nl < 1) { *info = -2; } else if (*nr < 1) { *info = -3; } else if (*sqre < 0 || *sqre > 1) { *info = -4; } else if (*ldgcol < n) { *info = -14; } else if (*ldgnum < n) { *info = -16; } if (*info != 0) { i__1 = -(*info); xerbla_("SLASD6", &i__1); return 0; } /* The following values are for bookkeeping purposes only. They are */ /* integer pointers which indicate the portion of the workspace */ /* used by a particular array in SLASD7 and SLASD8. */ isigma = 1; iw = isigma + n; ivfw = iw + m; ivlw = ivfw + m; idx = 1; idxc = idx + n; idxp = idxc + n; /* Scale. */ /* Computing MAX */ r__1 = dabs(*alpha), r__2 = dabs(*beta); orgnrm = dmax(r__1,r__2); d__[*nl + 1] = 0.f; i__1 = n; for (i__ = 1; i__ <= i__1; ++i__) { if ((r__1 = d__[i__], dabs(r__1)) > orgnrm) { orgnrm = (r__1 = d__[i__], dabs(r__1)); } /* L10: */ } slascl_("G", &c__0, &c__0, &orgnrm, &c_b7, &n, &c__1, &d__[1], &n, info); *alpha /= orgnrm; *beta /= orgnrm; /* Sort and Deflate singular values. */ slasd7_(icompq, nl, nr, sqre, k, &d__[1], &z__[1], &work[iw], &vf[1], & work[ivfw], &vl[1], &work[ivlw], alpha, beta, &work[isigma], & iwork[idx], &iwork[idxp], &idxq[1], &perm[1], givptr, &givcol[ givcol_offset], ldgcol, &givnum[givnum_offset], ldgnum, c__, s, info); /* Solve Secular Equation, compute DIFL, DIFR, and update VF, VL. */ slasd8_(icompq, k, &d__[1], &z__[1], &vf[1], &vl[1], &difl[1], &difr[1], ldgnum, &work[isigma], &work[iw], info); /* Save the poles if ICOMPQ = 1. */ if (*icompq == 1) { scopy_(k, &d__[1], &c__1, &poles[poles_dim1 + 1], &c__1); scopy_(k, &work[isigma], &c__1, &poles[(poles_dim1 << 1) + 1], &c__1); } /* Unscale. */ slascl_("G", &c__0, &c__0, &c_b7, &orgnrm, &n, &c__1, &d__[1], &n, info); /* Prepare the IDXQ sorting permutation. */ n1 = *k; n2 = n - *k; slamrg_(&n1, &n2, &d__[1], &c__1, &c_n1, &idxq[1]); return 0; /* End of SLASD6 */ } /* slasd6_ */