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NAME DORGQR - generate an M-by-N real matrix Q with orthonormal columns, SYNOPSIS SUBROUTINE DORGQR( M, N, K, A, LDA, TAU, WORK, LWORK, INFO ) INTEGER INFO, K, LDA, LWORK, M, N DOUBLE PRECISION A( LDA, * ), TAU( * ), WORK( LWORK ) PURPOSE DORGQR generates an M-by-N real matrix Q with orthonormal columns, which is defined as the first N columns of a pro- duct of K elementary reflectors of order M Q = H(1) H(2) . . . H(k) as returned by DGEQRF. 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) DOUBLE PRECISION array, dimension (LDA,N) On entry, the i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGEQRF in the first k columns of its array 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) DOUBLE PRECISION array, dimension (K) TAU(i) must contain the scalar factor of the elemen- tary reflector H(i), as returned by DGEQRF. WORK (workspace) DOUBLE PRECISION array, dimension (LWORK) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. LWORK (input) INTEGER The dimension of the array WORK. LWORK >= max(1,N). For optimum performance LWORK >= N*NB, where NB is the optimal blocksize. INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument has an illegal value