Subroutine */
| 3687 | } /* dgehrd_ */ |
| 3688 | |
| 3689 | /* Subroutine */ int dgelq2_(integer *m, integer *n, doublereal *a, integer * |
| 3690 | lda, doublereal *tau, doublereal *work, integer *info) |
| 3691 | { |
| 3692 | /* System generated locals */ |
| 3693 | integer a_dim1, a_offset, i__1, i__2, i__3; |
| 3694 | |
| 3695 | /* Local variables */ |
| 3696 | static integer i__, k; |
| 3697 | static doublereal aii; |
| 3698 | extern /* Subroutine */ int dlarf_(char *, integer *, integer *, |
| 3699 | doublereal *, integer *, doublereal *, doublereal *, integer *, |
| 3700 | doublereal *), dlarfg_(integer *, doublereal *, |
| 3701 | doublereal *, integer *, doublereal *), xerbla_(char *, integer *); |
| 3702 | |
| 3703 | |
| 3704 | /* |
| 3705 | -- LAPACK routine (version 3.2.2) -- |
| 3706 | -- LAPACK is a software package provided by Univ. of Tennessee, -- |
| 3707 | -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
| 3708 | June 2010 |
| 3709 | |
| 3710 | |
| 3711 | Purpose |
| 3712 | ======= |
| 3713 | |
| 3714 | DGELQ2 computes an LQ factorization of a real m by n matrix A: |
| 3715 | A = L * Q. |
| 3716 | |
| 3717 | Arguments |
| 3718 | ========= |
| 3719 | |
| 3720 | M (input) INTEGER |
| 3721 | The number of rows of the matrix A. M >= 0. |
| 3722 | |
| 3723 | N (input) INTEGER |
| 3724 | The number of columns of the matrix A. N >= 0. |
| 3725 | |
| 3726 | A (input/output) DOUBLE PRECISION array, dimension (LDA,N) |
| 3727 | On entry, the m by n matrix A. |
| 3728 | On exit, the elements on and below the diagonal of the array |
| 3729 | contain the m by min(m,n) lower trapezoidal matrix L (L is |
| 3730 | lower triangular if m <= n); the elements above the diagonal, |
| 3731 | with the array TAU, represent the orthogonal matrix Q as a |
| 3732 | product of elementary reflectors (see Further Details). |
| 3733 | |
| 3734 | LDA (input) INTEGER |
| 3735 | The leading dimension of the array A. LDA >= max(1,M). |
| 3736 | |
| 3737 | TAU (output) DOUBLE PRECISION array, dimension (min(M,N)) |
| 3738 | The scalar factors of the elementary reflectors (see Further |
| 3739 | Details). |
| 3740 | |
| 3741 | WORK (workspace) DOUBLE PRECISION array, dimension (M) |
| 3742 | |
| 3743 | INFO (output) INTEGER |
| 3744 | = 0: successful exit |
| 3745 | < 0: if INFO = -i, the i-th argument had an illegal value |
| 3746 |