sorg2l(3)

NAME

SORG2L - generate an m by n real matrix Q with orthonormal

columns,

SYNOPSIS

SUBROUTINE SORG2L( M, N, K, A, LDA, TAU, WORK, INFO )
    INTEGER        INFO, K, LDA, M, N
    REAL           A( LDA, * ), TAU( * ), WORK( * )

PURPOSE

SORG2L generates an m by n real matrix Q with orthonormal

columns, which is defined as the last n columns of a product of k

elementary reflectors of order m

Q = H(k) . . . H(2) H(1)

as returned by SGEQLF.

ARGUMENTS

M (input) INTEGER

The number of rows of the matrix Q. M >= 0.

N (input) INTEGER

The number of columns of the matrix Q. M >= N >=

0.

K (input) INTEGER

The number of elementary reflectors whose product

defines the matrix Q. N >= K >= 0.

A (input/output) REAL array, dimension (LDA,N)

On entry, the (n-k+i)-th column must contain the

vector which defines the elementary reflector H(i), for i =

1,2,...,k, as returned by SGEQLF in the last k columns of its ar

ray argument A. On exit, the m by n matrix Q.

LDA (input) INTEGER

The first dimension of the array A. LDA >=

max(1,M).

TAU (input) REAL array, dimension (K)

TAU(i) must contain the scalar factor of the ele

mentary reflector H(i), as returned by SGEQLF.

WORK (workspace) REAL array, dimension (N)

INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = -i, the i-th argument has an ille

gal value

LAPACK version 3.0 15 June 2000

SORG2L(3)