Functions | |
magma_int_t | magma_dgeqr2_gpu (magma_int_t m, magma_int_t n, magmaDouble_ptr dA, magma_int_t ldda, magmaDouble_ptr dtau, magmaDouble_ptr dwork, magma_int_t *info) |
DGEQR2 computes a QR factorization of a real m by n matrix A: A = Q * R using the non-blocking Householder QR. |
magma_int_t magma_dgeqr2_gpu | ( | magma_int_t | m, | |
magma_int_t | n, | |||
magmaDouble_ptr | dA, | |||
magma_int_t | ldda, | |||
magmaDouble_ptr | dtau, | |||
magmaDouble_ptr | dwork, | |||
magma_int_t * | info | |||
) |
DGEQR2 computes a QR factorization of a real m by n matrix A: A = Q * R using the non-blocking Householder QR.
[in] | m | INTEGER The number of rows of the matrix A. M >= 0. |
[in] | n | INTEGER The number of columns of the matrix A. N >= 0. |
[in,out] | dA | DOUBLE PRECISION 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 unitary matrix Q as a product of elementary reflectors (see Further Details). |
[in] | ldda | INTEGER The leading dimension of the array A. LDA >= max(1,M). |
[out] | dtau | DOUBLE PRECISION array, dimension (min(M,N)) The scalar factors of the elementary reflectors (see Further Details). |
dwork | (workspace) DOUBLE_PRECISION array, dimension (N) | |
[out] | info | INTEGER
|
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**H
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).