/* -- translated by f2c (version 20100827). 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" /* Table of constant values */ static integer c__0 = 0; static integer c__2 = 2; /* Subroutine */ int splicingdlasd0_(integer *n, integer *sqre, doublereal *d__, doublereal *e, doublereal *u, integer *ldu, doublereal *vt, integer * ldvt, integer *smlsiz, integer *iwork, doublereal *work, integer * info) { /* System generated locals */ integer u_dim1, u_offset, vt_dim1, vt_offset, i__1, i__2; /* Builtin functions */ integer pow_ii(integer *, integer *); /* Local variables */ static integer i__, j, m, i1, ic, lf, nd, ll, nl, nr, im1, ncc, nlf, nrf, iwk, lvl, ndb1, nlp1, nrp1; static doublereal beta; static integer idxq, nlvl; static doublereal alpha; static integer inode, ndiml, idxqc, ndimr, itemp, sqrei; extern /* Subroutine */ int splicingdlasd1_(integer *, integer *, integer *, doublereal *, doublereal *, doublereal *, doublereal *, integer *, doublereal *, integer *, integer *, integer *, doublereal *, integer *), splicingdlasdq_(char *, integer *, integer *, integer *, integer *, integer *, doublereal *, doublereal *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *), splicingdlasdt_(integer *, integer *, integer *, integer *, integer *, integer *, integer *), splicingxerbla_( char *, integer *, ftnlen); /* -- LAPACK auxiliary routine (version 3.2.2) -- -- LAPACK is a software package provided by Univ. of Tennessee, -- -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- June 2010 Purpose ======= Using a divide and conquer approach, DLASD0 computes the singular value decomposition (SVD) of a real upper bidiagonal N-by-M matrix B with diagonal D and offdiagonal E, where M = N + SQRE. The algorithm computes orthogonal matrices U and VT such that B = U * S * VT. The singular values S are overwritten on D. A related subroutine, DLASDA, computes only the singular values, and optionally, the singular vectors in compact form. Arguments ========= N (input) INTEGER On entry, the row dimension of the upper bidiagonal matrix. This is also the dimension of the main diagonal array D. SQRE (input) INTEGER Specifies the column dimension of the bidiagonal matrix. = 0: The bidiagonal matrix has column dimension M = N; = 1: The bidiagonal matrix has column dimension M = N+1; D (input/output) DOUBLE PRECISION array, dimension (N) On entry D contains the main diagonal of the bidiagonal matrix. On exit D, if INFO = 0, contains its singular values. E (input) DOUBLE PRECISION array, dimension (M-1) Contains the subdiagonal entries of the bidiagonal matrix. On exit, E has been destroyed. U (output) DOUBLE PRECISION array, dimension at least (LDQ, N) On exit, U contains the left singular vectors. LDU (input) INTEGER On entry, leading dimension of U. VT (output) DOUBLE PRECISION array, dimension at least (LDVT, M) On exit, VT**T contains the right singular vectors. LDVT (input) INTEGER On entry, leading dimension of VT. SMLSIZ (input) INTEGER On entry, maximum size of the subproblems at the bottom of the computation tree. IWORK (workspace) INTEGER work array. Dimension must be at least (8 * N) WORK (workspace) DOUBLE PRECISION work array. Dimension must be at least (3 * M**2 + 2 * M) INFO (output) INTEGER = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value. > 0: if INFO = 1, a 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 ===================================================================== Test the input parameters. Parameter adjustments */ --d__; --e; u_dim1 = *ldu; u_offset = 1 + u_dim1; u -= u_offset; vt_dim1 = *ldvt; vt_offset = 1 + vt_dim1; vt -= vt_offset; --iwork; --work; /* Function Body */ *info = 0; if (*n < 0) { *info = -1; } else if (*sqre < 0 || *sqre > 1) { *info = -2; } m = *n + *sqre; if (*ldu < *n) { *info = -6; } else if (*ldvt < m) { *info = -8; } else if (*smlsiz < 3) { *info = -9; } if (*info != 0) { i__1 = -(*info); splicingxerbla_("DLASD0", &i__1, (ftnlen)6); return 0; } /* If the input matrix is too small, call DLASDQ to find the SVD. */ if (*n <= *smlsiz) { splicingdlasdq_("U", sqre, n, &m, n, &c__0, &d__[1], &e[1], &vt[vt_offset], ldvt, &u[u_offset], ldu, &u[u_offset], ldu, &work[1], info); return 0; } /* Set up the computation tree. */ inode = 1; ndiml = inode + *n; ndimr = ndiml + *n; idxq = ndimr + *n; iwk = idxq + *n; splicingdlasdt_(n, &nlvl, &nd, &iwork[inode], &iwork[ndiml], &iwork[ndimr], smlsiz); /* For the nodes on bottom level of the tree, solve their subproblems by DLASDQ. */ ndb1 = (nd + 1) / 2; ncc = 0; i__1 = nd; for (i__ = ndb1; i__ <= i__1; ++i__) { /* IC : center row of each node NL : number of rows of left subproblem NR : number of rows of right subproblem NLF: starting row of the left subproblem NRF: starting row of the right subproblem */ i1 = i__ - 1; ic = iwork[inode + i1]; nl = iwork[ndiml + i1]; nlp1 = nl + 1; nr = iwork[ndimr + i1]; nrp1 = nr + 1; nlf = ic - nl; nrf = ic + 1; sqrei = 1; splicingdlasdq_("U", &sqrei, &nl, &nlp1, &nl, &ncc, &d__[nlf], &e[nlf], &vt[ nlf + nlf * vt_dim1], ldvt, &u[nlf + nlf * u_dim1], ldu, &u[ nlf + nlf * u_dim1], ldu, &work[1], info); if (*info != 0) { return 0; } itemp = idxq + nlf - 2; i__2 = nl; for (j = 1; j <= i__2; ++j) { iwork[itemp + j] = j; /* L10: */ } if (i__ == nd) { sqrei = *sqre; } else { sqrei = 1; } nrp1 = nr + sqrei; splicingdlasdq_("U", &sqrei, &nr, &nrp1, &nr, &ncc, &d__[nrf], &e[nrf], &vt[ nrf + nrf * vt_dim1], ldvt, &u[nrf + nrf * u_dim1], ldu, &u[ nrf + nrf * u_dim1], ldu, &work[1], info); if (*info != 0) { return 0; } itemp = idxq + ic; i__2 = nr; for (j = 1; j <= i__2; ++j) { iwork[itemp + j - 1] = j; /* L20: */ } /* L30: */ } /* Now conquer each subproblem bottom-up. */ for (lvl = nlvl; lvl >= 1; --lvl) { /* Find the first node LF and last node LL on the current level LVL. */ if (lvl == 1) { lf = 1; ll = 1; } else { i__1 = lvl - 1; lf = pow_ii(&c__2, &i__1); ll = (lf << 1) - 1; } i__1 = ll; for (i__ = lf; i__ <= i__1; ++i__) { im1 = i__ - 1; ic = iwork[inode + im1]; nl = iwork[ndiml + im1]; nr = iwork[ndimr + im1]; nlf = ic - nl; if (*sqre == 0 && i__ == ll) { sqrei = *sqre; } else { sqrei = 1; } idxqc = idxq + nlf - 1; alpha = d__[ic]; beta = e[ic]; splicingdlasd1_(&nl, &nr, &sqrei, &d__[nlf], &alpha, &beta, &u[nlf + nlf * u_dim1], ldu, &vt[nlf + nlf * vt_dim1], ldvt, &iwork[ idxqc], &iwork[iwk], &work[1], info); if (*info != 0) { return 0; } /* L40: */ } /* L50: */ } return 0; /* End of DLASD0 */ } /* splicingdlasd0_ */