--- /dev/null
+#include "clapack.h"
+
+/* Table of constant values */
+
+static integer c__1 = 1;
+static integer c_n1 = -1;
+static integer c__3 = 3;
+static integer c__2 = 2;
+
+/* Subroutine */ int sgeqrf_(integer *m, integer *n, real *a, integer *lda,
+ real *tau, real *work, integer *lwork, integer *info)
+{
+ /* System generated locals */
+ integer a_dim1, a_offset, i__1, i__2, i__3, i__4;
+
+ /* Local variables */
+ integer i__, k, ib, nb, nx, iws, nbmin, iinfo;
+ extern /* Subroutine */ int sgeqr2_(integer *, integer *, real *, integer
+ *, real *, real *, integer *), slarfb_(char *, char *, char *,
+ char *, integer *, integer *, integer *, real *, integer *, real *
+, integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *);
+ extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
+ integer *, integer *);
+ extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *,
+ real *, integer *, real *, real *, integer *);
+ integer ldwork, lwkopt;
+ logical lquery;
+
+
+/* -- LAPACK routine (version 3.1) -- */
+/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
+/* November 2006 */
+
+/* .. Scalar Arguments .. */
+/* .. */
+/* .. Array Arguments .. */
+/* .. */
+
+/* Purpose */
+/* ======= */
+
+/* SGEQRF computes a QR factorization of a real M-by-N matrix A: */
+/* A = Q * R. */
+
+/* Arguments */
+/* ========= */
+
+/* M (input) INTEGER */
+/* The number of rows of the matrix A. M >= 0. */
+
+/* N (input) INTEGER */
+/* The number of columns of the matrix A. N >= 0. */
+
+/* A (input/output) REAL array, dimension (LDA,N) */
+/* On entry, the M-by-N matrix A. */
+/* On exit, the elements on and above the diagonal of the array */
+/* contain the min(M,N)-by-N upper trapezoidal matrix R (R is */
+/* upper triangular if m >= n); the elements below the diagonal, */
+/* with the array TAU, represent the orthogonal matrix Q as a */
+/* product of min(m,n) elementary reflectors (see Further */
+/* Details). */
+
+/* LDA (input) INTEGER */
+/* The leading dimension of the array A. LDA >= max(1,M). */
+
+/* TAU (output) REAL array, dimension (min(M,N)) */
+/* The scalar factors of the elementary reflectors (see Further */
+/* Details). */
+
+/* WORK (workspace/output) REAL array, dimension (MAX(1,LWORK)) */
+/* On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
+
+/* LWORK (input) INTEGER */
+/* The dimension of the array WORK. LWORK >= max(1,N). */
+/* For optimum performance LWORK >= N*NB, where NB is */
+/* the optimal blocksize. */
+
+/* If LWORK = -1, then a workspace query is assumed; the routine */
+/* only calculates the optimal size of the WORK array, returns */
+/* this value as the first entry of the WORK array, and no error */
+/* message related to LWORK is issued by XERBLA. */
+
+/* INFO (output) INTEGER */
+/* = 0: successful exit */
+/* < 0: if INFO = -i, the i-th argument had an illegal value */
+
+/* Further Details */
+/* =============== */
+
+/* The matrix Q is represented as a product of elementary reflectors */
+
+/* Q = H(1) H(2) . . . H(k), where k = min(m,n). */
+
+/* Each H(i) has the form */
+
+/* H(i) = I - tau * v * v' */
+
+/* where tau is a real scalar, and v is a real vector with */
+/* v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i), */
+/* and tau in TAU(i). */
+
+/* ===================================================================== */
+
+/* .. Local Scalars .. */
+/* .. */
+/* .. External Subroutines .. */
+/* .. */
+/* .. Intrinsic Functions .. */
+/* .. */
+/* .. External Functions .. */
+/* .. */
+/* .. Executable Statements .. */
+
+/* Test the input arguments */
+
+ /* Parameter adjustments */
+ a_dim1 = *lda;
+ a_offset = 1 + a_dim1;
+ a -= a_offset;
+ --tau;
+ --work;
+
+ /* Function Body */
+ *info = 0;
+ nb = ilaenv_(&c__1, "SGEQRF", " ", m, n, &c_n1, &c_n1);
+ lwkopt = *n * nb;
+ work[1] = (real) lwkopt;
+ lquery = *lwork == -1;
+ if (*m < 0) {
+ *info = -1;
+ } else if (*n < 0) {
+ *info = -2;
+ } else if (*lda < max(1,*m)) {
+ *info = -4;
+ } else if (*lwork < max(1,*n) && ! lquery) {
+ *info = -7;
+ }
+ if (*info != 0) {
+ i__1 = -(*info);
+ xerbla_("SGEQRF", &i__1);
+ return 0;
+ } else if (lquery) {
+ return 0;
+ }
+
+/* Quick return if possible */
+
+ k = min(*m,*n);
+ if (k == 0) {
+ work[1] = 1.f;
+ return 0;
+ }
+
+ nbmin = 2;
+ nx = 0;
+ iws = *n;
+ if (nb > 1 && nb < k) {
+
+/* Determine when to cross over from blocked to unblocked code. */
+
+/* Computing MAX */
+ i__1 = 0, i__2 = ilaenv_(&c__3, "SGEQRF", " ", m, n, &c_n1, &c_n1);
+ nx = max(i__1,i__2);
+ if (nx < k) {
+
+/* Determine if workspace is large enough for blocked code. */
+
+ ldwork = *n;
+ iws = ldwork * nb;
+ if (*lwork < iws) {
+
+/* Not enough workspace to use optimal NB: reduce NB and */
+/* determine the minimum value of NB. */
+
+ nb = *lwork / ldwork;
+/* Computing MAX */
+ i__1 = 2, i__2 = ilaenv_(&c__2, "SGEQRF", " ", m, n, &c_n1, &
+ c_n1);
+ nbmin = max(i__1,i__2);
+ }
+ }
+ }
+
+ if (nb >= nbmin && nb < k && nx < k) {
+
+/* Use blocked code initially */
+
+ i__1 = k - nx;
+ i__2 = nb;
+ for (i__ = 1; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) {
+/* Computing MIN */
+ i__3 = k - i__ + 1;
+ ib = min(i__3,nb);
+
+/* Compute the QR factorization of the current block */
+/* A(i:m,i:i+ib-1) */
+
+ i__3 = *m - i__ + 1;
+ sgeqr2_(&i__3, &ib, &a[i__ + i__ * a_dim1], lda, &tau[i__], &work[
+ 1], &iinfo);
+ if (i__ + ib <= *n) {
+
+/* Form the triangular factor of the block reflector */
+/* H = H(i) H(i+1) . . . H(i+ib-1) */
+
+ i__3 = *m - i__ + 1;
+ slarft_("Forward", "Columnwise", &i__3, &ib, &a[i__ + i__ *
+ a_dim1], lda, &tau[i__], &work[1], &ldwork);
+
+/* Apply H' to A(i:m,i+ib:n) from the left */
+
+ i__3 = *m - i__ + 1;
+ i__4 = *n - i__ - ib + 1;
+ slarfb_("Left", "Transpose", "Forward", "Columnwise", &i__3, &
+ i__4, &ib, &a[i__ + i__ * a_dim1], lda, &work[1], &
+ ldwork, &a[i__ + (i__ + ib) * a_dim1], lda, &work[ib
+ + 1], &ldwork);
+ }
+/* L10: */
+ }
+ } else {
+ i__ = 1;
+ }
+
+/* Use unblocked code to factor the last or only block. */
+
+ if (i__ <= k) {
+ i__2 = *m - i__ + 1;
+ i__1 = *n - i__ + 1;
+ sgeqr2_(&i__2, &i__1, &a[i__ + i__ * a_dim1], lda, &tau[i__], &work[1]
+, &iinfo);
+ }
+
+ work[1] = (real) iws;
+ return 0;
+
+/* End of SGEQRF */
+
+} /* sgeqrf_ */
projects / opencv / blobdiff