/* -- 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__1 = 1; /* Subroutine */ int splicingdgebd2_(integer *m, integer *n, doublereal *a, integer * lda, doublereal *d__, doublereal *e, doublereal *tauq, doublereal * taup, doublereal *work, integer *info) { /* System generated locals */ integer a_dim1, a_offset, i__1, i__2, i__3; /* Local variables */ static integer i__; extern /* Subroutine */ int splicingdlarf_(char *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, doublereal *), splicingdlarfg_(integer *, doublereal *, doublereal *, integer *, doublereal *), splicingxerbla_(char *, integer *, ftnlen); /* -- LAPACK routine (version 3.3.1) -- -- LAPACK is a software package provided by Univ. of Tennessee, -- -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- -- April 2011 -- Purpose ======= DGEBD2 reduces a real general m by n matrix A to upper or lower bidiagonal form B by an orthogonal transformation: Q**T * A * P = B. If m >= n, B is upper bidiagonal; if m < n, B is lower bidiagonal. Arguments ========= M (input) INTEGER The number of rows in the matrix A. M >= 0. N (input) INTEGER The number of columns in the matrix A. N >= 0. A (input/output) DOUBLE PRECISION array, dimension (LDA,N) On entry, the m by n general matrix to be reduced. On exit, if m >= n, the diagonal and the first superdiagonal are overwritten with the upper bidiagonal matrix B; the elements below the diagonal, with the array TAUQ, represent the orthogonal matrix Q as a product of elementary reflectors, and the elements above the first superdiagonal, with the array TAUP, represent the orthogonal matrix P as a product of elementary reflectors; if m < n, the diagonal and the first subdiagonal are overwritten with the lower bidiagonal matrix B; the elements below the first subdiagonal, with the array TAUQ, represent the orthogonal matrix Q as a product of elementary reflectors, and the elements above the diagonal, with the array TAUP, represent the orthogonal matrix P as a product of elementary reflectors. See Further Details. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,M). D (output) DOUBLE PRECISION array, dimension (min(M,N)) The diagonal elements of the bidiagonal matrix B: D(i) = A(i,i). E (output) DOUBLE PRECISION array, dimension (min(M,N)-1) The off-diagonal elements of the bidiagonal matrix B: if m >= n, E(i) = A(i,i+1) for i = 1,2,...,n-1; if m < n, E(i) = A(i+1,i) for i = 1,2,...,m-1. TAUQ (output) DOUBLE PRECISION array dimension (min(M,N)) The scalar factors of the elementary reflectors which represent the orthogonal matrix Q. See Further Details. TAUP (output) DOUBLE PRECISION array, dimension (min(M,N)) The scalar factors of the elementary reflectors which represent the orthogonal matrix P. See Further Details. WORK (workspace) DOUBLE PRECISION array, dimension (max(M,N)) INFO (output) INTEGER = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value. Further Details =============== The matrices Q and P are represented as products of elementary reflectors: If m >= n, Q = H(1) H(2) . . . H(n) and P = G(1) G(2) . . . G(n-1) Each H(i) and G(i) has the form: H(i) = I - tauq * v * v**T and G(i) = I - taup * u * u**T where tauq and taup are real scalars, and v and u are real vectors; v(1:i-1) = 0, v(i) = 1, and v(i+1:m) is stored on exit in A(i+1:m,i); u(1:i) = 0, u(i+1) = 1, and u(i+2:n) is stored on exit in A(i,i+2:n); tauq is stored in TAUQ(i) and taup in TAUP(i). If m < n, Q = H(1) H(2) . . . H(m-1) and P = G(1) G(2) . . . G(m) Each H(i) and G(i) has the form: H(i) = I - tauq * v * v**T and G(i) = I - taup * u * u**T where tauq and taup are real scalars, and v and u are real vectors; v(1:i) = 0, v(i+1) = 1, and v(i+2:m) is stored on exit in A(i+2:m,i); u(1:i-1) = 0, u(i) = 1, and u(i+1:n) is stored on exit in A(i,i+1:n); tauq is stored in TAUQ(i) and taup in TAUP(i). The contents of A on exit are illustrated by the following examples: m = 6 and n = 5 (m > n): m = 5 and n = 6 (m < n): ( d e u1 u1 u1 ) ( d u1 u1 u1 u1 u1 ) ( v1 d e u2 u2 ) ( e d u2 u2 u2 u2 ) ( v1 v2 d e u3 ) ( v1 e d u3 u3 u3 ) ( v1 v2 v3 d e ) ( v1 v2 e d u4 u4 ) ( v1 v2 v3 v4 d ) ( v1 v2 v3 e d u5 ) ( v1 v2 v3 v4 v5 ) where d and e denote diagonal and off-diagonal elements of B, vi denotes an element of the vector defining H(i), and ui an element of the vector defining G(i). ===================================================================== Test the input parameters Parameter adjustments */ a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; --d__; --e; --tauq; --taup; --work; /* Function Body */ *info = 0; if (*m < 0) { *info = -1; } else if (*n < 0) { *info = -2; } else if (*lda < max(1,*m)) { *info = -4; } if (*info < 0) { i__1 = -(*info); splicingxerbla_("DGEBD2", &i__1, (ftnlen)6); return 0; } if (*m >= *n) { /* Reduce to upper bidiagonal form */ i__1 = *n; for (i__ = 1; i__ <= i__1; ++i__) { /* Generate elementary reflector H(i) to annihilate A(i+1:m,i) */ i__2 = *m - i__ + 1; /* Computing MIN */ i__3 = i__ + 1; splicingdlarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[min(i__3,*m) + i__ * a_dim1], &c__1, &tauq[i__]); d__[i__] = a[i__ + i__ * a_dim1]; a[i__ + i__ * a_dim1] = 1.; /* Apply H(i) to A(i:m,i+1:n) from the left */ if (i__ < *n) { i__2 = *m - i__ + 1; i__3 = *n - i__; splicingdlarf_("Left", &i__2, &i__3, &a[i__ + i__ * a_dim1], &c__1, & tauq[i__], &a[i__ + (i__ + 1) * a_dim1], lda, &work[1] ); } a[i__ + i__ * a_dim1] = d__[i__]; if (i__ < *n) { /* Generate elementary reflector G(i) to annihilate A(i,i+2:n) */ i__2 = *n - i__; /* Computing MIN */ i__3 = i__ + 2; splicingdlarfg_(&i__2, &a[i__ + (i__ + 1) * a_dim1], &a[i__ + min( i__3,*n) * a_dim1], lda, &taup[i__]); e[i__] = a[i__ + (i__ + 1) * a_dim1]; a[i__ + (i__ + 1) * a_dim1] = 1.; /* Apply G(i) to A(i+1:m,i+1:n) from the right */ i__2 = *m - i__; i__3 = *n - i__; splicingdlarf_("Right", &i__2, &i__3, &a[i__ + (i__ + 1) * a_dim1], lda, &taup[i__], &a[i__ + 1 + (i__ + 1) * a_dim1], lda, &work[1]); a[i__ + (i__ + 1) * a_dim1] = e[i__]; } else { taup[i__] = 0.; } /* L10: */ } } else { /* Reduce to lower bidiagonal form */ i__1 = *m; for (i__ = 1; i__ <= i__1; ++i__) { /* Generate elementary reflector G(i) to annihilate A(i,i+1:n) */ i__2 = *n - i__ + 1; /* Computing MIN */ i__3 = i__ + 1; splicingdlarfg_(&i__2, &a[i__ + i__ * a_dim1], &a[i__ + min(i__3,*n) * a_dim1], lda, &taup[i__]); d__[i__] = a[i__ + i__ * a_dim1]; a[i__ + i__ * a_dim1] = 1.; /* Apply G(i) to A(i+1:m,i:n) from the right */ if (i__ < *m) { i__2 = *m - i__; i__3 = *n - i__ + 1; splicingdlarf_("Right", &i__2, &i__3, &a[i__ + i__ * a_dim1], lda, & taup[i__], &a[i__ + 1 + i__ * a_dim1], lda, &work[1]); } a[i__ + i__ * a_dim1] = d__[i__]; if (i__ < *m) { /* Generate elementary reflector H(i) to annihilate A(i+2:m,i) */ i__2 = *m - i__; /* Computing MIN */ i__3 = i__ + 2; splicingdlarfg_(&i__2, &a[i__ + 1 + i__ * a_dim1], &a[min(i__3,*m) + i__ * a_dim1], &c__1, &tauq[i__]); e[i__] = a[i__ + 1 + i__ * a_dim1]; a[i__ + 1 + i__ * a_dim1] = 1.; /* Apply H(i) to A(i+1:m,i+1:n) from the left */ i__2 = *m - i__; i__3 = *n - i__; splicingdlarf_("Left", &i__2, &i__3, &a[i__ + 1 + i__ * a_dim1], & c__1, &tauq[i__], &a[i__ + 1 + (i__ + 1) * a_dim1], lda, &work[1]); a[i__ + 1 + i__ * a_dim1] = e[i__]; } else { tauq[i__] = 0.; } /* L20: */ } } return 0; /* End of DGEBD2 */ } /* splicingdgebd2_ */