#include "clapack.h" /* Table of constant values */ static doublereal c_b15 = -.125; static integer c__1 = 1; static doublereal c_b49 = 1.; static doublereal c_b72 = -1.; /* Subroutine */ int dbdsqr_(char *uplo, integer *n, integer *ncvt, integer * nru, integer *ncc, doublereal *d__, doublereal *e, doublereal *vt, integer *ldvt, doublereal *u, integer *ldu, doublereal *c__, integer * ldc, doublereal *work, integer *info) { /* System generated locals */ integer c_dim1, c_offset, u_dim1, u_offset, vt_dim1, vt_offset, i__1, i__2; doublereal d__1, d__2, d__3, d__4; /* Builtin functions */ double pow_dd(doublereal *, doublereal *), sqrt(doublereal), d_sign( doublereal *, doublereal *); /* Local variables */ doublereal f, g, h__; integer i__, j, m; doublereal r__, cs; integer ll; doublereal sn, mu; integer nm1, nm12, nm13, lll; doublereal eps, sll, tol, abse; integer idir; doublereal abss; integer oldm; doublereal cosl; integer isub, iter; doublereal unfl, sinl, cosr, smin, smax, sinr; extern /* Subroutine */ int drot_(integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, doublereal *), dlas2_( doublereal *, doublereal *, doublereal *, doublereal *, doublereal *), dscal_(integer *, doublereal *, doublereal *, integer *); extern logical lsame_(char *, char *); doublereal oldcs; extern /* Subroutine */ int dlasr_(char *, char *, char *, integer *, integer *, doublereal *, doublereal *, doublereal *, integer *); integer oldll; doublereal shift, sigmn, oldsn; extern /* Subroutine */ int dswap_(integer *, doublereal *, integer *, doublereal *, integer *); integer maxit; doublereal sminl, sigmx; logical lower; extern /* Subroutine */ int dlasq1_(integer *, doublereal *, doublereal *, doublereal *, integer *), dlasv2_(doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *); extern doublereal dlamch_(char *); extern /* Subroutine */ int dlartg_(doublereal *, doublereal *, doublereal *, doublereal *, doublereal *), xerbla_(char *, integer *); doublereal sminoa, thresh; logical rotate; doublereal tolmul; /* -- LAPACK routine (version 3.1.1) -- */ /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ /* January 2007 */ /* .. Scalar Arguments .. */ /* .. */ /* .. Array Arguments .. */ /* .. */ /* Purpose */ /* ======= */ /* DBDSQR computes the singular values and, optionally, the right and/or */ /* left singular vectors from the singular value decomposition (SVD) of */ /* a real N-by-N (upper or lower) bidiagonal matrix B using the implicit */ /* zero-shift QR algorithm. The SVD of B has the form */ /* B = Q * S * P**T */ /* where S is the diagonal matrix of singular values, Q is an orthogonal */ /* matrix of left singular vectors, and P is an orthogonal matrix of */ /* right singular vectors. If left singular vectors are requested, this */ /* subroutine actually returns U*Q instead of Q, and, if right singular */ /* vectors are requested, this subroutine returns P**T*VT instead of */ /* P**T, for given real input matrices U and VT. When U and VT are the */ /* orthogonal matrices that reduce a general matrix A to bidiagonal */ /* form: A = U*B*VT, as computed by DGEBRD, then */ /* A = (U*Q) * S * (P**T*VT) */ /* is the SVD of A. Optionally, the subroutine may also compute Q**T*C */ /* for a given real input matrix C. */ /* See "Computing Small Singular Values of Bidiagonal Matrices With */ /* Guaranteed High Relative Accuracy," by J. Demmel and W. Kahan, */ /* LAPACK Working Note #3 (or SIAM J. Sci. Statist. Comput. vol. 11, */ /* no. 5, pp. 873-912, Sept 1990) and */ /* "Accurate singular values and differential qd algorithms," by */ /* B. Parlett and V. Fernando, Technical Report CPAM-554, Mathematics */ /* Department, University of California at Berkeley, July 1992 */ /* for a detailed description of the algorithm. */ /* Arguments */ /* ========= */ /* UPLO (input) CHARACTER*1 */ /* = 'U': B is upper bidiagonal; */ /* = 'L': B is lower bidiagonal. */ /* N (input) INTEGER */ /* The order of the matrix B. N >= 0. */ /* NCVT (input) INTEGER */ /* The number of columns of the matrix VT. NCVT >= 0. */ /* NRU (input) INTEGER */ /* The number of rows of the matrix U. NRU >= 0. */ /* NCC (input) INTEGER */ /* The number of columns of the matrix C. NCC >= 0. */ /* D (input/output) DOUBLE PRECISION array, dimension (N) */ /* On entry, the n diagonal elements of the bidiagonal matrix B. */ /* On exit, if INFO=0, the singular values of B in decreasing */ /* order. */ /* E (input/output) DOUBLE PRECISION array, dimension (N-1) */ /* On entry, the N-1 offdiagonal elements of the bidiagonal */ /* matrix B. */ /* On exit, if INFO = 0, E is destroyed; if INFO > 0, D and E */ /* will contain the diagonal and superdiagonal elements of a */ /* bidiagonal matrix orthogonally equivalent to the one given */ /* as input. */ /* VT (input/output) DOUBLE PRECISION array, dimension (LDVT, NCVT) */ /* On entry, an N-by-NCVT matrix VT. */ /* On exit, VT is overwritten by P**T * VT. */ /* Not referenced if NCVT = 0. */ /* LDVT (input) INTEGER */ /* The leading dimension of the array VT. */ /* LDVT >= max(1,N) if NCVT > 0; LDVT >= 1 if NCVT = 0. */ /* U (input/output) DOUBLE PRECISION array, dimension (LDU, N) */ /* On entry, an NRU-by-N matrix U. */ /* On exit, U is overwritten by U * Q. */ /* Not referenced if NRU = 0. */ /* LDU (input) INTEGER */ /* The leading dimension of the array U. LDU >= max(1,NRU). */ /* C (input/output) DOUBLE PRECISION array, dimension (LDC, NCC) */ /* On entry, an N-by-NCC matrix C. */ /* On exit, C is overwritten by Q**T * C. */ /* Not referenced if NCC = 0. */ /* LDC (input) INTEGER */ /* The leading dimension of the array C. */ /* LDC >= max(1,N) if NCC > 0; LDC >=1 if NCC = 0. */ /* WORK (workspace) DOUBLE PRECISION array, dimension (2*N) */ /* if NCVT = NRU = NCC = 0, (max(1, 4*N)) otherwise */ /* INFO (output) INTEGER */ /* = 0: successful exit */ /* < 0: If INFO = -i, the i-th argument had an illegal value */ /* > 0: the algorithm did not converge; D and E contain the */ /* elements of a bidiagonal matrix which is orthogonally */ /* similar to the input matrix B; if INFO = i, i */ /* elements of E have not converged to zero. */ /* Internal Parameters */ /* =================== */ /* TOLMUL DOUBLE PRECISION, default = max(10,min(100,EPS**(-1/8))) */ /* TOLMUL controls the convergence criterion of the QR loop. */ /* If it is positive, TOLMUL*EPS is the desired relative */ /* precision in the computed singular values. */ /* If it is negative, abs(TOLMUL*EPS*sigma_max) is the */ /* desired absolute accuracy in the computed singular */ /* values (corresponds to relative accuracy */ /* abs(TOLMUL*EPS) in the largest singular value. */ /* abs(TOLMUL) should be between 1 and 1/EPS, and preferably */ /* between 10 (for fast convergence) and .1/EPS */ /* (for there to be some accuracy in the results). */ /* Default is to lose at either one eighth or 2 of the */ /* available decimal digits in each computed singular value */ /* (whichever is smaller). */ /* MAXITR INTEGER, default = 6 */ /* MAXITR controls the maximum number of passes of the */ /* algorithm through its inner loop. The algorithms stops */ /* (and so fails to converge) if the number of passes */ /* through the inner loop exceeds MAXITR*N**2. */ /* ===================================================================== */ /* .. Parameters .. */ /* .. */ /* .. Local Scalars .. */ /* .. */ /* .. External Functions .. */ /* .. */ /* .. External Subroutines .. */ /* .. */ /* .. Intrinsic Functions .. */ /* .. */ /* .. Executable Statements .. */ /* Test the input parameters. */ /* Parameter adjustments */ --d__; --e; vt_dim1 = *ldvt; vt_offset = 1 + vt_dim1; vt -= vt_offset; u_dim1 = *ldu; u_offset = 1 + u_dim1; u -= u_offset; c_dim1 = *ldc; c_offset = 1 + c_dim1; c__ -= c_offset; --work; /* Function Body */ *info = 0; lower = lsame_(uplo, "L"); if (! lsame_(uplo, "U") && ! lower) { *info = -1; } else if (*n < 0) { *info = -2; } else if (*ncvt < 0) { *info = -3; } else if (*nru < 0) { *info = -4; } else if (*ncc < 0) { *info = -5; } else if (*ncvt == 0 && *ldvt < 1 || *ncvt > 0 && *ldvt < max(1,*n)) { *info = -9; } else if (*ldu < max(1,*nru)) { *info = -11; } else if (*ncc == 0 && *ldc < 1 || *ncc > 0 && *ldc < max(1,*n)) { *info = -13; } if (*info != 0) { i__1 = -(*info); xerbla_("DBDSQR", &i__1); return 0; } if (*n == 0) { return 0; } if (*n == 1) { goto L160; } /* ROTATE is true if any singular vectors desired, false otherwise */ rotate = *ncvt > 0 || *nru > 0 || *ncc > 0; /* If no singular vectors desired, use qd algorithm */ if (! rotate) { dlasq1_(n, &d__[1], &e[1], &work[1], info); return 0; } nm1 = *n - 1; nm12 = nm1 + nm1; nm13 = nm12 + nm1; idir = 0; /* Get machine constants */ eps = dlamch_("Epsilon"); unfl = dlamch_("Safe minimum"); /* If matrix lower bidiagonal, rotate to be upper bidiagonal */ /* by applying Givens rotations on the left */ if (lower) { i__1 = *n - 1; for (i__ = 1; i__ <= i__1; ++i__) { dlartg_(&d__[i__], &e[i__], &cs, &sn, &r__); d__[i__] = r__; e[i__] = sn * d__[i__ + 1]; d__[i__ + 1] = cs * d__[i__ + 1]; work[i__] = cs; work[nm1 + i__] = sn; /* L10: */ } /* Update singular vectors if desired */ if (*nru > 0) { dlasr_("R", "V", "F", nru, n, &work[1], &work[*n], &u[u_offset], ldu); } if (*ncc > 0) { dlasr_("L", "V", "F", n, ncc, &work[1], &work[*n], &c__[c_offset], ldc); } } /* Compute singular values to relative accuracy TOL */ /* (By setting TOL to be negative, algorithm will compute */ /* singular values to absolute accuracy ABS(TOL)*norm(input matrix)) */ /* Computing MAX */ /* Computing MIN */ d__3 = 100., d__4 = pow_dd(&eps, &c_b15); d__1 = 10., d__2 = min(d__3,d__4); tolmul = max(d__1,d__2); tol = tolmul * eps; /* Compute approximate maximum, minimum singular values */ smax = 0.; i__1 = *n; for (i__ = 1; i__ <= i__1; ++i__) { /* Computing MAX */ d__2 = smax, d__3 = (d__1 = d__[i__], abs(d__1)); smax = max(d__2,d__3); /* L20: */ } i__1 = *n - 1; for (i__ = 1; i__ <= i__1; ++i__) { /* Computing MAX */ d__2 = smax, d__3 = (d__1 = e[i__], abs(d__1)); smax = max(d__2,d__3); /* L30: */ } sminl = 0.; if (tol >= 0.) { /* Relative accuracy desired */ sminoa = abs(d__[1]); if (sminoa == 0.) { goto L50; } mu = sminoa; i__1 = *n; for (i__ = 2; i__ <= i__1; ++i__) { mu = (d__2 = d__[i__], abs(d__2)) * (mu / (mu + (d__1 = e[i__ - 1] , abs(d__1)))); sminoa = min(sminoa,mu); if (sminoa == 0.) { goto L50; } /* L40: */ } L50: sminoa /= sqrt((doublereal) (*n)); /* Computing MAX */ d__1 = tol * sminoa, d__2 = *n * 6 * *n * unfl; thresh = max(d__1,d__2); } else { /* Absolute accuracy desired */ /* Computing MAX */ d__1 = abs(tol) * smax, d__2 = *n * 6 * *n * unfl; thresh = max(d__1,d__2); } /* Prepare for main iteration loop for the singular values */ /* (MAXIT is the maximum number of passes through the inner */ /* loop permitted before nonconvergence signalled.) */ maxit = *n * 6 * *n; iter = 0; oldll = -1; oldm = -1; /* M points to last element of unconverged part of matrix */ m = *n; /* Begin main iteration loop */ L60: /* Check for convergence or exceeding iteration count */ if (m <= 1) { goto L160; } if (iter > maxit) { goto L200; } /* Find diagonal block of matrix to work on */ if (tol < 0. && (d__1 = d__[m], abs(d__1)) <= thresh) { d__[m] = 0.; } smax = (d__1 = d__[m], abs(d__1)); smin = smax; i__1 = m - 1; for (lll = 1; lll <= i__1; ++lll) { ll = m - lll; abss = (d__1 = d__[ll], abs(d__1)); abse = (d__1 = e[ll], abs(d__1)); if (tol < 0. && abss <= thresh) { d__[ll] = 0.; } if (abse <= thresh) { goto L80; } smin = min(smin,abss); /* Computing MAX */ d__1 = max(smax,abss); smax = max(d__1,abse); /* L70: */ } ll = 0; goto L90; L80: e[ll] = 0.; /* Matrix splits since E(LL) = 0 */ if (ll == m - 1) { /* Convergence of bottom singular value, return to top of loop */ --m; goto L60; } L90: ++ll; /* E(LL) through E(M-1) are nonzero, E(LL-1) is zero */ if (ll == m - 1) { /* 2 by 2 block, handle separately */ dlasv2_(&d__[m - 1], &e[m - 1], &d__[m], &sigmn, &sigmx, &sinr, &cosr, &sinl, &cosl); d__[m - 1] = sigmx; e[m - 1] = 0.; d__[m] = sigmn; /* Compute singular vectors, if desired */ if (*ncvt > 0) { drot_(ncvt, &vt[m - 1 + vt_dim1], ldvt, &vt[m + vt_dim1], ldvt, & cosr, &sinr); } if (*nru > 0) { drot_(nru, &u[(m - 1) * u_dim1 + 1], &c__1, &u[m * u_dim1 + 1], & c__1, &cosl, &sinl); } if (*ncc > 0) { drot_(ncc, &c__[m - 1 + c_dim1], ldc, &c__[m + c_dim1], ldc, & cosl, &sinl); } m += -2; goto L60; } /* If working on new submatrix, choose shift direction */ /* (from larger end diagonal element towards smaller) */ if (ll > oldm || m < oldll) { if ((d__1 = d__[ll], abs(d__1)) >= (d__2 = d__[m], abs(d__2))) { /* Chase bulge from top (big end) to bottom (small end) */ idir = 1; } else { /* Chase bulge from bottom (big end) to top (small end) */ idir = 2; } } /* Apply convergence tests */ if (idir == 1) { /* Run convergence test in forward direction */ /* First apply standard test to bottom of matrix */ if ((d__2 = e[m - 1], abs(d__2)) <= abs(tol) * (d__1 = d__[m], abs( d__1)) || tol < 0. && (d__3 = e[m - 1], abs(d__3)) <= thresh) { e[m - 1] = 0.; goto L60; } if (tol >= 0.) { /* If relative accuracy desired, */ /* apply convergence criterion forward */ mu = (d__1 = d__[ll], abs(d__1)); sminl = mu; i__1 = m - 1; for (lll = ll; lll <= i__1; ++lll) { if ((d__1 = e[lll], abs(d__1)) <= tol * mu) { e[lll] = 0.; goto L60; } mu = (d__2 = d__[lll + 1], abs(d__2)) * (mu / (mu + (d__1 = e[ lll], abs(d__1)))); sminl = min(sminl,mu); /* L100: */ } } } else { /* Run convergence test in backward direction */ /* First apply standard test to top of matrix */ if ((d__2 = e[ll], abs(d__2)) <= abs(tol) * (d__1 = d__[ll], abs(d__1) ) || tol < 0. && (d__3 = e[ll], abs(d__3)) <= thresh) { e[ll] = 0.; goto L60; } if (tol >= 0.) { /* If relative accuracy desired, */ /* apply convergence criterion backward */ mu = (d__1 = d__[m], abs(d__1)); sminl = mu; i__1 = ll; for (lll = m - 1; lll >= i__1; --lll) { if ((d__1 = e[lll], abs(d__1)) <= tol * mu) { e[lll] = 0.; goto L60; } mu = (d__2 = d__[lll], abs(d__2)) * (mu / (mu + (d__1 = e[lll] , abs(d__1)))); sminl = min(sminl,mu); /* L110: */ } } } oldll = ll; oldm = m; /* Compute shift. First, test if shifting would ruin relative */ /* accuracy, and if so set the shift to zero. */ /* Computing MAX */ d__1 = eps, d__2 = tol * .01; if (tol >= 0. && *n * tol * (sminl / smax) <= max(d__1,d__2)) { /* Use a zero shift to avoid loss of relative accuracy */ shift = 0.; } else { /* Compute the shift from 2-by-2 block at end of matrix */ if (idir == 1) { sll = (d__1 = d__[ll], abs(d__1)); dlas2_(&d__[m - 1], &e[m - 1], &d__[m], &shift, &r__); } else { sll = (d__1 = d__[m], abs(d__1)); dlas2_(&d__[ll], &e[ll], &d__[ll + 1], &shift, &r__); } /* Test if shift negligible, and if so set to zero */ if (sll > 0.) { /* Computing 2nd power */ d__1 = shift / sll; if (d__1 * d__1 < eps) { shift = 0.; } } } /* Increment iteration count */ iter = iter + m - ll; /* If SHIFT = 0, do simplified QR iteration */ if (shift == 0.) { if (idir == 1) { /* Chase bulge from top to bottom */ /* Save cosines and sines for later singular vector updates */ cs = 1.; oldcs = 1.; i__1 = m - 1; for (i__ = ll; i__ <= i__1; ++i__) { d__1 = d__[i__] * cs; dlartg_(&d__1, &e[i__], &cs, &sn, &r__); if (i__ > ll) { e[i__ - 1] = oldsn * r__; } d__1 = oldcs * r__; d__2 = d__[i__ + 1] * sn; dlartg_(&d__1, &d__2, &oldcs, &oldsn, &d__[i__]); work[i__ - ll + 1] = cs; work[i__ - ll + 1 + nm1] = sn; work[i__ - ll + 1 + nm12] = oldcs; work[i__ - ll + 1 + nm13] = oldsn; /* L120: */ } h__ = d__[m] * cs; d__[m] = h__ * oldcs; e[m - 1] = h__ * oldsn; /* Update singular vectors */ if (*ncvt > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "F", &i__1, ncvt, &work[1], &work[*n], &vt[ ll + vt_dim1], ldvt); } if (*nru > 0) { i__1 = m - ll + 1; dlasr_("R", "V", "F", nru, &i__1, &work[nm12 + 1], &work[nm13 + 1], &u[ll * u_dim1 + 1], ldu); } if (*ncc > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "F", &i__1, ncc, &work[nm12 + 1], &work[nm13 + 1], &c__[ll + c_dim1], ldc); } /* Test convergence */ if ((d__1 = e[m - 1], abs(d__1)) <= thresh) { e[m - 1] = 0.; } } else { /* Chase bulge from bottom to top */ /* Save cosines and sines for later singular vector updates */ cs = 1.; oldcs = 1.; i__1 = ll + 1; for (i__ = m; i__ >= i__1; --i__) { d__1 = d__[i__] * cs; dlartg_(&d__1, &e[i__ - 1], &cs, &sn, &r__); if (i__ < m) { e[i__] = oldsn * r__; } d__1 = oldcs * r__; d__2 = d__[i__ - 1] * sn; dlartg_(&d__1, &d__2, &oldcs, &oldsn, &d__[i__]); work[i__ - ll] = cs; work[i__ - ll + nm1] = -sn; work[i__ - ll + nm12] = oldcs; work[i__ - ll + nm13] = -oldsn; /* L130: */ } h__ = d__[ll] * cs; d__[ll] = h__ * oldcs; e[ll] = h__ * oldsn; /* Update singular vectors */ if (*ncvt > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "B", &i__1, ncvt, &work[nm12 + 1], &work[ nm13 + 1], &vt[ll + vt_dim1], ldvt); } if (*nru > 0) { i__1 = m - ll + 1; dlasr_("R", "V", "B", nru, &i__1, &work[1], &work[*n], &u[ll * u_dim1 + 1], ldu); } if (*ncc > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "B", &i__1, ncc, &work[1], &work[*n], &c__[ ll + c_dim1], ldc); } /* Test convergence */ if ((d__1 = e[ll], abs(d__1)) <= thresh) { e[ll] = 0.; } } } else { /* Use nonzero shift */ if (idir == 1) { /* Chase bulge from top to bottom */ /* Save cosines and sines for later singular vector updates */ f = ((d__1 = d__[ll], abs(d__1)) - shift) * (d_sign(&c_b49, &d__[ ll]) + shift / d__[ll]); g = e[ll]; i__1 = m - 1; for (i__ = ll; i__ <= i__1; ++i__) { dlartg_(&f, &g, &cosr, &sinr, &r__); if (i__ > ll) { e[i__ - 1] = r__; } f = cosr * d__[i__] + sinr * e[i__]; e[i__] = cosr * e[i__] - sinr * d__[i__]; g = sinr * d__[i__ + 1]; d__[i__ + 1] = cosr * d__[i__ + 1]; dlartg_(&f, &g, &cosl, &sinl, &r__); d__[i__] = r__; f = cosl * e[i__] + sinl * d__[i__ + 1]; d__[i__ + 1] = cosl * d__[i__ + 1] - sinl * e[i__]; if (i__ < m - 1) { g = sinl * e[i__ + 1]; e[i__ + 1] = cosl * e[i__ + 1]; } work[i__ - ll + 1] = cosr; work[i__ - ll + 1 + nm1] = sinr; work[i__ - ll + 1 + nm12] = cosl; work[i__ - ll + 1 + nm13] = sinl; /* L140: */ } e[m - 1] = f; /* Update singular vectors */ if (*ncvt > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "F", &i__1, ncvt, &work[1], &work[*n], &vt[ ll + vt_dim1], ldvt); } if (*nru > 0) { i__1 = m - ll + 1; dlasr_("R", "V", "F", nru, &i__1, &work[nm12 + 1], &work[nm13 + 1], &u[ll * u_dim1 + 1], ldu); } if (*ncc > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "F", &i__1, ncc, &work[nm12 + 1], &work[nm13 + 1], &c__[ll + c_dim1], ldc); } /* Test convergence */ if ((d__1 = e[m - 1], abs(d__1)) <= thresh) { e[m - 1] = 0.; } } else { /* Chase bulge from bottom to top */ /* Save cosines and sines for later singular vector updates */ f = ((d__1 = d__[m], abs(d__1)) - shift) * (d_sign(&c_b49, &d__[m] ) + shift / d__[m]); g = e[m - 1]; i__1 = ll + 1; for (i__ = m; i__ >= i__1; --i__) { dlartg_(&f, &g, &cosr, &sinr, &r__); if (i__ < m) { e[i__] = r__; } f = cosr * d__[i__] + sinr * e[i__ - 1]; e[i__ - 1] = cosr * e[i__ - 1] - sinr * d__[i__]; g = sinr * d__[i__ - 1]; d__[i__ - 1] = cosr * d__[i__ - 1]; dlartg_(&f, &g, &cosl, &sinl, &r__); d__[i__] = r__; f = cosl * e[i__ - 1] + sinl * d__[i__ - 1]; d__[i__ - 1] = cosl * d__[i__ - 1] - sinl * e[i__ - 1]; if (i__ > ll + 1) { g = sinl * e[i__ - 2]; e[i__ - 2] = cosl * e[i__ - 2]; } work[i__ - ll] = cosr; work[i__ - ll + nm1] = -sinr; work[i__ - ll + nm12] = cosl; work[i__ - ll + nm13] = -sinl; /* L150: */ } e[ll] = f; /* Test convergence */ if ((d__1 = e[ll], abs(d__1)) <= thresh) { e[ll] = 0.; } /* Update singular vectors if desired */ if (*ncvt > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "B", &i__1, ncvt, &work[nm12 + 1], &work[ nm13 + 1], &vt[ll + vt_dim1], ldvt); } if (*nru > 0) { i__1 = m - ll + 1; dlasr_("R", "V", "B", nru, &i__1, &work[1], &work[*n], &u[ll * u_dim1 + 1], ldu); } if (*ncc > 0) { i__1 = m - ll + 1; dlasr_("L", "V", "B", &i__1, ncc, &work[1], &work[*n], &c__[ ll + c_dim1], ldc); } } } /* QR iteration finished, go back and check convergence */ goto L60; /* All singular values converged, so make them positive */ L160: i__1 = *n; for (i__ = 1; i__ <= i__1; ++i__) { if (d__[i__] < 0.) { d__[i__] = -d__[i__]; /* Change sign of singular vectors, if desired */ if (*ncvt > 0) { dscal_(ncvt, &c_b72, &vt[i__ + vt_dim1], ldvt); } } /* L170: */ } /* Sort the singular values into decreasing order (insertion sort on */ /* singular values, but only one transposition per singular vector) */ i__1 = *n - 1; for (i__ = 1; i__ <= i__1; ++i__) { /* Scan for smallest D(I) */ isub = 1; smin = d__[1]; i__2 = *n + 1 - i__; for (j = 2; j <= i__2; ++j) { if (d__[j] <= smin) { isub = j; smin = d__[j]; } /* L180: */ } if (isub != *n + 1 - i__) { /* Swap singular values and vectors */ d__[isub] = d__[*n + 1 - i__]; d__[*n + 1 - i__] = smin; if (*ncvt > 0) { dswap_(ncvt, &vt[isub + vt_dim1], ldvt, &vt[*n + 1 - i__ + vt_dim1], ldvt); } if (*nru > 0) { dswap_(nru, &u[isub * u_dim1 + 1], &c__1, &u[(*n + 1 - i__) * u_dim1 + 1], &c__1); } if (*ncc > 0) { dswap_(ncc, &c__[isub + c_dim1], ldc, &c__[*n + 1 - i__ + c_dim1], ldc); } } /* L190: */ } goto L220; /* Maximum number of iterations exceeded, failure to converge */ L200: *info = 0; i__1 = *n - 1; for (i__ = 1; i__ <= i__1; ++i__) { if (e[i__] != 0.) { ++(*info); } /* L210: */ } L220: return 0; /* End of DBDSQR */ } /* dbdsqr_ */