Visible to Intel only — GUID: GUID-BEB99750-51C5-4A0D-874E-4E0813775AF4
Visible to Intel only — GUID: GUID-BEB99750-51C5-4A0D-874E-4E0813775AF4
?laqp2
Computes a QR factorization with column pivoting of the matrix block.
Syntax
call slaqp2( m, n, offset, a, lda, jpvt, tau, vn1, vn2, work )
call dlaqp2( m, n, offset, a, lda, jpvt, tau, vn1, vn2, work )
call claqp2( m, n, offset, a, lda, jpvt, tau, vn1, vn2, work )
call zlaqp2( m, n, offset, a, lda, jpvt, tau, vn1, vn2, work )
Include Files
- mkl.fi
Description
The routine computes a QR factorization with column pivoting of the block A(offset+1:m,1:n). The block A(1:offset,1:n) is accordingly pivoted, but not factorized.
Input Parameters
- m
-
INTEGER. The number of rows of the matrix A. m≥ 0.
- n
-
INTEGER. The number of columns of the matrix A. n≥ 0.
- offset
-
INTEGER. The number of rows of the matrix A that must be pivoted but no factorized. offset≥ 0.
- a
-
REAL for slaqp2
DOUBLE PRECISION for dlaqp2
COMPLEX for claqp2
DOUBLE COMPLEX for zlaqp2
Array, DIMENSION (lda,n). On entry, the m-by-n matrix A.
- lda
-
INTEGER. The leading dimension of the array a. lda≥ max(1,m).
- jpvt
-
INTEGER.
Array, DIMENSION (n).
On entry, if jpvt(i) ≠ 0, the i-th column of A is permuted to the front of A*P (a leading column); if jpvt(i) = 0, the i-th column of A is a free column.
- vn1, vn2
-
REAL for slaqp2/claqp2
DOUBLE PRECISION for dlaqp2/zlaqp2
Arrays, DIMENSION (n) each. Contain the vectors with the partial and exact column norms, respectively.
- work
-
REAL for slaqp2
DOUBLE PRECISION for dlaqp2
COMPLEX for claqp2
DOUBLE COMPLEX for zlaqp2 Workspace array, DIMENSION (n).
Output Parameters
- a
-
On exit, the upper triangle of block A(offset+1:m,1:n) is the triangular factor obtained; the elements in block A(offset+1:m,1:n) below the diagonal, together with the array tau, represent the orthogonal matrix Q as a product of elementary reflectors. Block A(1:offset,1:n) has been accordingly pivoted, but not factorized.
- jpvt
-
On exit, if jpvt(i) = k, then the i-th column of A*P was the k-th column of A.
- tau
-
REAL for slaqp2
DOUBLE PRECISION for dlaqp2
COMPLEX for claqp2
DOUBLE COMPLEX for zlaqp2
Array, DIMENSION(min(m,n)).
The scalar factors of the elementary reflectors.
- vn1, vn2
-
Contain the vectors with the partial and exact column norms, respectively.