dtzrqf (l)  Linux Man Pages
dtzrqf: routine i deprecated and has been replaced by routine DTZRZF
NAME
DTZRQF  routine i deprecated and has been replaced by routine DTZRZFSYNOPSIS
 SUBROUTINE DTZRQF(
 M, N, A, LDA, TAU, INFO )
 INTEGER INFO, LDA, M, N
 DOUBLE PRECISION A( LDA, * ), TAU( * )
PURPOSE
This routine is deprecated and has been replaced by routine DTZRZF. DTZRQF reduces the MbyN ( M<=N ) real upper trapezoidal matrix A to upper triangular form by means of orthogonal transformations. The upper trapezoidal matrix A is factored asA
where Z is an NbyN orthogonal matrix and R is an MbyM upper triangular matrix.
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 >= M.
 A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
 On entry, the leading MbyN upper trapezoidal part of the array A must contain the matrix to be factorized. On exit, the leading MbyM upper triangular part of A contains the upper triangular matrix R, and elements M+1 to N of the first M rows of A, with the array TAU, represent the orthogonal matrix Z as a product of M elementary reflectors.
 LDA (input) INTEGER
 The leading dimension of the array A. LDA >= max(1,M).
 TAU (output) DOUBLE PRECISION array, dimension (M)
 The scalar factors of the elementary reflectors.
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
FURTHER DETAILS
The factorization is obtained by Householderaqs method. The kth transformation matrix, Z( k ), which is used to introduce zeros into the ( m  k + 1 )th row of A, is given in the formZ(
where
T(
The scalar tau is returned in the kth element of TAU and the vector u( k ) in the kth row of A, such that the elements of z( k ) are in a( k, m + 1 ), ..., a( k, n ). The elements of R are returned in the upper triangular part of A.
Z is given by
Z