/* slabrd.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 real c_b4 = -1.f; static real c_b5 = 1.f; static integer c__1 = 1; static real c_b16 = 0.f; /* Subroutine */ int slabrd_(integer *m, integer *n, integer *nb, real *a, integer *lda, real *d__, real *e, real *tauq, real *taup, real *x, integer *ldx, real *y, integer *ldy) { /* System generated locals */ integer a_dim1, a_offset, x_dim1, x_offset, y_dim1, y_offset, i__1, i__2, i__3; /* Local variables */ integer i__; extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), sgemv_(char *, integer *, integer *, real *, real *, integer *, real *, integer *, real *, real *, integer *), slarfg_( integer *, real *, real *, integer *, real *); /* -- LAPACK auxiliary routine (version 3.2) -- */ /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ /* November 2006 */ /* .. Scalar Arguments .. */ /* .. */ /* .. Array Arguments .. */ /* .. */ /* Purpose */ /* ======= */ /* SLABRD reduces the first NB rows and columns of a real general */ /* m by n matrix A to upper or lower bidiagonal form by an orthogonal */ /* transformation Q' * A * P, and returns the matrices X and Y which */ /* are needed to apply the transformation to the unreduced part of A. */ /* If m >= n, A is reduced to upper bidiagonal form; if m < n, to lower */ /* bidiagonal form. */ /* This is an auxiliary routine called by SGEBRD */ /* Arguments */ /* ========= */ /* M (input) INTEGER */ /* The number of rows in the matrix A. */ /* N (input) INTEGER */ /* The number of columns in the matrix A. */ /* NB (input) INTEGER */ /* The number of leading rows and columns of A to be reduced. */ /* A (input/output) REAL array, dimension (LDA,N) */ /* On entry, the m by n general matrix to be reduced. */ /* On exit, the first NB rows and columns of the matrix are */ /* overwritten; the rest of the array is unchanged. */ /* If m >= n, elements on and below the diagonal in the first NB */ /* columns, with the array TAUQ, represent the orthogonal */ /* matrix Q as a product of elementary reflectors; and */ /* elements above the diagonal in the first NB rows, with the */ /* array TAUP, represent the orthogonal matrix P as a product */ /* of elementary reflectors. */ /* If m < n, elements below the diagonal in the first NB */ /* columns, with the array TAUQ, represent the orthogonal */ /* matrix Q as a product of elementary reflectors, and */ /* elements on and above the diagonal in the first NB rows, */ /* 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) REAL array, dimension (NB) */ /* The diagonal elements of the first NB rows and columns of */ /* the reduced matrix. D(i) = A(i,i). */ /* E (output) REAL array, dimension (NB) */ /* The off-diagonal elements of the first NB rows and columns of */ /* the reduced matrix. */ /* TAUQ (output) REAL array dimension (NB) */ /* The scalar factors of the elementary reflectors which */ /* represent the orthogonal matrix Q. See Further Details. */ /* TAUP (output) REAL array, dimension (NB) */ /* The scalar factors of the elementary reflectors which */ /* represent the orthogonal matrix P. See Further Details. */ /* X (output) REAL array, dimension (LDX,NB) */ /* The m-by-nb matrix X required to update the unreduced part */ /* of A. */ /* LDX (input) INTEGER */ /* The leading dimension of the array X. LDX >= M. */ /* Y (output) REAL array, dimension (LDY,NB) */ /* The n-by-nb matrix Y required to update the unreduced part */ /* of A. */ /* LDY (input) INTEGER */ /* The leading dimension of the array Y. LDY >= N. */ /* Further Details */ /* =============== */ /* The matrices Q and P are represented as products of elementary */ /* reflectors: */ /* Q = H(1) H(2) . . . H(nb) and P = G(1) G(2) . . . G(nb) */ /* Each H(i) and G(i) has the form: */ /* H(i) = I - tauq * v * v' and G(i) = I - taup * u * u' */ /* where tauq and taup are real scalars, and v and u are real vectors. */ /* If m >= n, v(1:i-1) = 0, v(i) = 1, and v(i:m) is stored on exit in */ /* A(i:m,i); u(1:i) = 0, u(i+1) = 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). */ /* If m < n, v(1:i) = 0, v(i+1) = 1, and v(i+1:m) is stored on exit in */ /* A(i+2:m,i); u(1:i-1) = 0, u(i) = 1, and u(i:n) is stored on exit in */ /* A(i,i+1:n); tauq is stored in TAUQ(i) and taup in TAUP(i). */ /* The elements of the vectors v and u together form the m-by-nb matrix */ /* V and the nb-by-n matrix U' which are needed, with X and Y, to apply */ /* the transformation to the unreduced part of the matrix, using a block */ /* update of the form: A := A - V*Y' - X*U'. */ /* The contents of A on exit are illustrated by the following examples */ /* with nb = 2: */ /* m = 6 and n = 5 (m > n): m = 5 and n = 6 (m < n): */ /* ( 1 1 u1 u1 u1 ) ( 1 u1 u1 u1 u1 u1 ) */ /* ( v1 1 1 u2 u2 ) ( 1 1 u2 u2 u2 u2 ) */ /* ( v1 v2 a a a ) ( v1 1 a a a a ) */ /* ( v1 v2 a a a ) ( v1 v2 a a a a ) */ /* ( v1 v2 a a a ) ( v1 v2 a a a a ) */ /* ( v1 v2 a a a ) */ /* where a denotes an element of the original matrix which is unchanged, */ /* vi denotes an element of the vector defining H(i), and ui an element */ /* of the vector defining G(i). */ /* ===================================================================== */ /* .. Parameters .. */ /* .. */ /* .. Local Scalars .. */ /* .. */ /* .. External Subroutines .. */ /* .. */ /* .. Intrinsic Functions .. */ /* .. */ /* .. Executable Statements .. */ /* Quick return if possible */ /* Parameter adjustments */ a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; --d__; --e; --tauq; --taup; x_dim1 = *ldx; x_offset = 1 + x_dim1; x -= x_offset; y_dim1 = *ldy; y_offset = 1 + y_dim1; y -= y_offset; /* Function Body */ if (*m <= 0 || *n <= 0) { return 0; } if (*m >= *n) { /* Reduce to upper bidiagonal form */ i__1 = *nb; for (i__ = 1; i__ <= i__1; ++i__) { /* Update A(i:m,i) */ i__2 = *m - i__ + 1; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &a[i__ + a_dim1], lda, &y[i__ + y_dim1], ldy, &c_b5, &a[i__ + i__ * a_dim1], & c__1); i__2 = *m - i__ + 1; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &x[i__ + x_dim1], ldx, &a[i__ * a_dim1 + 1], &c__1, &c_b5, &a[i__ + i__ * a_dim1], &c__1); /* Generate reflection Q(i) to annihilate A(i+1:m,i) */ i__2 = *m - i__ + 1; /* Computing MIN */ i__3 = i__ + 1; slarfg_(&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]; if (i__ < *n) { a[i__ + i__ * a_dim1] = 1.f; /* Compute Y(i+1:n,i) */ i__2 = *m - i__ + 1; i__3 = *n - i__; sgemv_("Transpose", &i__2, &i__3, &c_b5, &a[i__ + (i__ + 1) * a_dim1], lda, &a[i__ + i__ * a_dim1], &c__1, &c_b16, & y[i__ + 1 + i__ * y_dim1], &c__1); i__2 = *m - i__ + 1; i__3 = i__ - 1; sgemv_("Transpose", &i__2, &i__3, &c_b5, &a[i__ + a_dim1], lda, &a[i__ + i__ * a_dim1], &c__1, &c_b16, &y[i__ * y_dim1 + 1], &c__1); i__2 = *n - i__; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &y[i__ + 1 + y_dim1], ldy, &y[i__ * y_dim1 + 1], &c__1, &c_b5, &y[ i__ + 1 + i__ * y_dim1], &c__1); i__2 = *m - i__ + 1; i__3 = i__ - 1; sgemv_("Transpose", &i__2, &i__3, &c_b5, &x[i__ + x_dim1], ldx, &a[i__ + i__ * a_dim1], &c__1, &c_b16, &y[i__ * y_dim1 + 1], &c__1); i__2 = i__ - 1; i__3 = *n - i__; sgemv_("Transpose", &i__2, &i__3, &c_b4, &a[(i__ + 1) * a_dim1 + 1], lda, &y[i__ * y_dim1 + 1], &c__1, &c_b5, &y[i__ + 1 + i__ * y_dim1], &c__1); i__2 = *n - i__; sscal_(&i__2, &tauq[i__], &y[i__ + 1 + i__ * y_dim1], &c__1); /* Update A(i,i+1:n) */ i__2 = *n - i__; sgemv_("No transpose", &i__2, &i__, &c_b4, &y[i__ + 1 + y_dim1], ldy, &a[i__ + a_dim1], lda, &c_b5, &a[i__ + ( i__ + 1) * a_dim1], lda); i__2 = i__ - 1; i__3 = *n - i__; sgemv_("Transpose", &i__2, &i__3, &c_b4, &a[(i__ + 1) * a_dim1 + 1], lda, &x[i__ + x_dim1], ldx, &c_b5, &a[ i__ + (i__ + 1) * a_dim1], lda); /* Generate reflection P(i) to annihilate A(i,i+2:n) */ i__2 = *n - i__; /* Computing MIN */ i__3 = i__ + 2; slarfg_(&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.f; /* Compute X(i+1:m,i) */ i__2 = *m - i__; i__3 = *n - i__; sgemv_("No transpose", &i__2, &i__3, &c_b5, &a[i__ + 1 + (i__ + 1) * a_dim1], lda, &a[i__ + (i__ + 1) * a_dim1], lda, &c_b16, &x[i__ + 1 + i__ * x_dim1], &c__1); i__2 = *n - i__; sgemv_("Transpose", &i__2, &i__, &c_b5, &y[i__ + 1 + y_dim1], ldy, &a[i__ + (i__ + 1) * a_dim1], lda, &c_b16, &x[ i__ * x_dim1 + 1], &c__1); i__2 = *m - i__; sgemv_("No transpose", &i__2, &i__, &c_b4, &a[i__ + 1 + a_dim1], lda, &x[i__ * x_dim1 + 1], &c__1, &c_b5, &x[ i__ + 1 + i__ * x_dim1], &c__1); i__2 = i__ - 1; i__3 = *n - i__; sgemv_("No transpose", &i__2, &i__3, &c_b5, &a[(i__ + 1) * a_dim1 + 1], lda, &a[i__ + (i__ + 1) * a_dim1], lda, & c_b16, &x[i__ * x_dim1 + 1], &c__1); i__2 = *m - i__; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &x[i__ + 1 + x_dim1], ldx, &x[i__ * x_dim1 + 1], &c__1, &c_b5, &x[ i__ + 1 + i__ * x_dim1], &c__1); i__2 = *m - i__; sscal_(&i__2, &taup[i__], &x[i__ + 1 + i__ * x_dim1], &c__1); } /* L10: */ } } else { /* Reduce to lower bidiagonal form */ i__1 = *nb; for (i__ = 1; i__ <= i__1; ++i__) { /* Update A(i,i:n) */ i__2 = *n - i__ + 1; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &y[i__ + y_dim1], ldy, &a[i__ + a_dim1], lda, &c_b5, &a[i__ + i__ * a_dim1], lda); i__2 = i__ - 1; i__3 = *n - i__ + 1; sgemv_("Transpose", &i__2, &i__3, &c_b4, &a[i__ * a_dim1 + 1], lda, &x[i__ + x_dim1], ldx, &c_b5, &a[i__ + i__ * a_dim1], lda); /* Generate reflection P(i) to annihilate A(i,i+1:n) */ i__2 = *n - i__ + 1; /* Computing MIN */ i__3 = i__ + 1; slarfg_(&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]; if (i__ < *m) { a[i__ + i__ * a_dim1] = 1.f; /* Compute X(i+1:m,i) */ i__2 = *m - i__; i__3 = *n - i__ + 1; sgemv_("No transpose", &i__2, &i__3, &c_b5, &a[i__ + 1 + i__ * a_dim1], lda, &a[i__ + i__ * a_dim1], lda, &c_b16, & x[i__ + 1 + i__ * x_dim1], &c__1); i__2 = *n - i__ + 1; i__3 = i__ - 1; sgemv_("Transpose", &i__2, &i__3, &c_b5, &y[i__ + y_dim1], ldy, &a[i__ + i__ * a_dim1], lda, &c_b16, &x[i__ * x_dim1 + 1], &c__1); i__2 = *m - i__; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &a[i__ + 1 + a_dim1], lda, &x[i__ * x_dim1 + 1], &c__1, &c_b5, &x[ i__ + 1 + i__ * x_dim1], &c__1); i__2 = i__ - 1; i__3 = *n - i__ + 1; sgemv_("No transpose", &i__2, &i__3, &c_b5, &a[i__ * a_dim1 + 1], lda, &a[i__ + i__ * a_dim1], lda, &c_b16, &x[i__ * x_dim1 + 1], &c__1); i__2 = *m - i__; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &x[i__ + 1 + x_dim1], ldx, &x[i__ * x_dim1 + 1], &c__1, &c_b5, &x[ i__ + 1 + i__ * x_dim1], &c__1); i__2 = *m - i__; sscal_(&i__2, &taup[i__], &x[i__ + 1 + i__ * x_dim1], &c__1); /* Update A(i+1:m,i) */ i__2 = *m - i__; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &a[i__ + 1 + a_dim1], lda, &y[i__ + y_dim1], ldy, &c_b5, &a[i__ + 1 + i__ * a_dim1], &c__1); i__2 = *m - i__; sgemv_("No transpose", &i__2, &i__, &c_b4, &x[i__ + 1 + x_dim1], ldx, &a[i__ * a_dim1 + 1], &c__1, &c_b5, &a[ i__ + 1 + i__ * a_dim1], &c__1); /* Generate reflection Q(i) to annihilate A(i+2:m,i) */ i__2 = *m - i__; /* Computing MIN */ i__3 = i__ + 2; slarfg_(&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.f; /* Compute Y(i+1:n,i) */ i__2 = *m - i__; i__3 = *n - i__; sgemv_("Transpose", &i__2, &i__3, &c_b5, &a[i__ + 1 + (i__ + 1) * a_dim1], lda, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b16, &y[i__ + 1 + i__ * y_dim1], &c__1); i__2 = *m - i__; i__3 = i__ - 1; sgemv_("Transpose", &i__2, &i__3, &c_b5, &a[i__ + 1 + a_dim1], lda, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b16, &y[ i__ * y_dim1 + 1], &c__1); i__2 = *n - i__; i__3 = i__ - 1; sgemv_("No transpose", &i__2, &i__3, &c_b4, &y[i__ + 1 + y_dim1], ldy, &y[i__ * y_dim1 + 1], &c__1, &c_b5, &y[ i__ + 1 + i__ * y_dim1], &c__1); i__2 = *m - i__; sgemv_("Transpose", &i__2, &i__, &c_b5, &x[i__ + 1 + x_dim1], ldx, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b16, &y[ i__ * y_dim1 + 1], &c__1); i__2 = *n - i__; sgemv_("Transpose", &i__, &i__2, &c_b4, &a[(i__ + 1) * a_dim1 + 1], lda, &y[i__ * y_dim1 + 1], &c__1, &c_b5, &y[i__ + 1 + i__ * y_dim1], &c__1); i__2 = *n - i__; sscal_(&i__2, &tauq[i__], &y[i__ + 1 + i__ * y_dim1], &c__1); } /* L20: */ } } return 0; /* End of SLABRD */ } /* slabrd_ */