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SUBROUTINE <a name="ZUNGQL.1"></a><a href="zungql.f.html#ZUNGQL.1">ZUNGQL</a>( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> -- LAPACK routine (version 3.1) --
</span><span class="comment">*</span><span class="comment"> Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
</span><span class="comment">*</span><span class="comment"> November 2006
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> .. Scalar Arguments ..
</span> INTEGER INFO, K, LDA, LWORK, M, N
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Array Arguments ..
</span> COMPLEX*16 A( LDA, * ), TAU( * ), WORK( * )
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Purpose
</span><span class="comment">*</span><span class="comment"> =======
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> <a name="ZUNGQL.17"></a><a href="zungql.f.html#ZUNGQL.1">ZUNGQL</a> generates an M-by-N complex matrix Q with orthonormal columns,
</span><span class="comment">*</span><span class="comment"> which is defined as the last N columns of a product of K elementary
</span><span class="comment">*</span><span class="comment"> reflectors of order M
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Q = H(k) . . . H(2) H(1)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> as returned by <a name="ZGEQLF.23"></a><a href="zgeqlf.f.html#ZGEQLF.1">ZGEQLF</a>.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Arguments
</span><span class="comment">*</span><span class="comment"> =========
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> M (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The number of rows of the matrix Q. M >= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> N (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The number of columns of the matrix Q. M >= N >= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> K (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The number of elementary reflectors whose product defines the
</span><span class="comment">*</span><span class="comment"> matrix Q. N >= K >= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> A (input/output) COMPLEX*16 array, dimension (LDA,N)
</span><span class="comment">*</span><span class="comment"> On entry, the (n-k+i)-th column must contain the vector which
</span><span class="comment">*</span><span class="comment"> defines the elementary reflector H(i), for i = 1,2,...,k, as
</span><span class="comment">*</span><span class="comment"> returned by <a name="ZGEQLF.41"></a><a href="zgeqlf.f.html#ZGEQLF.1">ZGEQLF</a> in the last k columns of its array
</span><span class="comment">*</span><span class="comment"> argument A.
</span><span class="comment">*</span><span class="comment"> On exit, the M-by-N matrix Q.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> LDA (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The first dimension of the array A. LDA >= max(1,M).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> TAU (input) COMPLEX*16 array, dimension (K)
</span><span class="comment">*</span><span class="comment"> TAU(i) must contain the scalar factor of the elementary
</span><span class="comment">*</span><span class="comment"> reflector H(i), as returned by <a name="ZGEQLF.50"></a><a href="zgeqlf.f.html#ZGEQLF.1">ZGEQLF</a>.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> WORK (workspace/output) COMPLEX*16 array, dimension (MAX(1,LWORK))
</span><span class="comment">*</span><span class="comment"> On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> LWORK (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The dimension of the array WORK. LWORK >= max(1,N).
</span><span class="comment">*</span><span class="comment"> For optimum performance LWORK >= N*NB, where NB is the
</span><span class="comment">*</span><span class="comment"> optimal blocksize.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> If LWORK = -1, then a workspace query is assumed; the routine
</span><span class="comment">*</span><span class="comment"> only calculates the optimal size of the WORK array, returns
</span><span class="comment">*</span><span class="comment"> this value as the first entry of the WORK array, and no error
</span><span class="comment">*</span><span class="comment"> message related to LWORK is issued by <a name="XERBLA.63"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> INFO (output) INTEGER
</span><span class="comment">*</span><span class="comment"> = 0: successful exit
</span><span class="comment">*</span><span class="comment"> < 0: if INFO = -i, the i-th argument has an illegal value
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> .. Parameters ..
</span> COMPLEX*16 ZERO
PARAMETER ( ZERO = ( 0.0D+0, 0.0D+0 ) )
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Local Scalars ..
</span> LOGICAL LQUERY
INTEGER I, IB, IINFO, IWS, J, KK, L, LDWORK, LWKOPT,
$ NB, NBMIN, NX
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. External Subroutines ..
</span> EXTERNAL <a name="XERBLA.81"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>, <a name="ZLARFB.81"></a><a href="zlarfb.f.html#ZLARFB.1">ZLARFB</a>, <a name="ZLARFT.81"></a><a href="zlarft.f.html#ZLARFT.1">ZLARFT</a>, <a name="ZUNG2L.81"></a><a href="zung2l.f.html#ZUNG2L.1">ZUNG2L</a>
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Intrinsic Functions ..
</span> INTRINSIC MAX, MIN
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. External Functions ..
</span> INTEGER <a name="ILAENV.87"></a><a href="hfy-index.html#ILAENV">ILAENV</a>
EXTERNAL <a name="ILAENV.88"></a><a href="hfy-index.html#ILAENV">ILAENV</a>
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Executable Statements ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Test the input arguments
</span><span class="comment">*</span><span class="comment">
</span> INFO = 0
LQUERY = ( LWORK.EQ.-1 )
IF( M.LT.0 ) THEN
INFO = -1
ELSE IF( N.LT.0 .OR. N.GT.M ) THEN
INFO = -2
ELSE IF( K.LT.0 .OR. K.GT.N ) THEN
INFO = -3
ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
INFO = -5
END IF
<span class="comment">*</span><span class="comment">
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