--- rpl/lapack/lapack/zgehrd.f 2011/07/22 07:38:14 1.8 +++ rpl/lapack/lapack/zgehrd.f 2011/11/21 20:43:09 1.9 @@ -1,9 +1,177 @@ +*> \brief \b ZGEHRD +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +*> \htmlonly +*> Download ZGEHRD + dependencies +*> +*> [TGZ] +*> +*> [ZIP] +*> +*> [TXT] +*> \endhtmlonly +* +* Definition: +* =========== +* +* SUBROUTINE ZGEHRD( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO ) +* +* .. Scalar Arguments .. +* INTEGER IHI, ILO, INFO, LDA, LWORK, N +* .. +* .. Array Arguments .. +* COMPLEX*16 A( LDA, * ), TAU( * ), WORK( * ) +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> ZGEHRD reduces a complex general matrix A to upper Hessenberg form H by +*> an unitary similarity transformation: Q**H * A * Q = H . +*> \endverbatim +* +* Arguments: +* ========== +* +*> \param[in] N +*> \verbatim +*> N is INTEGER +*> The order of the matrix A. N >= 0. +*> \endverbatim +*> +*> \param[in] ILO +*> \verbatim +*> ILO is INTEGER +*> \endverbatim +*> +*> \param[in] IHI +*> \verbatim +*> IHI is INTEGER +*> +*> It is assumed that A is already upper triangular in rows +*> and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally +*> set by a previous call to ZGEBAL; otherwise they should be +*> set to 1 and N respectively. See Further Details. +*> 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. +*> \endverbatim +*> +*> \param[in,out] A +*> \verbatim +*> A is COMPLEX*16 array, dimension (LDA,N) +*> On entry, the N-by-N general matrix to be reduced. +*> On exit, the upper triangle and the first subdiagonal of A +*> are overwritten with the upper Hessenberg matrix H, and the +*> elements below the first subdiagonal, with the array TAU, +*> represent the unitary matrix Q as a product of elementary +*> reflectors. See Further Details. +*> \endverbatim +*> +*> \param[in] LDA +*> \verbatim +*> LDA is INTEGER +*> The leading dimension of the array A. LDA >= max(1,N). +*> \endverbatim +*> +*> \param[out] TAU +*> \verbatim +*> TAU is COMPLEX*16 array, dimension (N-1) +*> The scalar factors of the elementary reflectors (see Further +*> Details). Elements 1:ILO-1 and IHI:N-1 of TAU are set to +*> zero. +*> \endverbatim +*> +*> \param[out] WORK +*> \verbatim +*> WORK is COMPLEX*16 array, dimension (LWORK) +*> On exit, if INFO = 0, WORK(1) returns the optimal LWORK. +*> \endverbatim +*> +*> \param[in] LWORK +*> \verbatim +*> LWORK is INTEGER +*> The length of the array WORK. LWORK >= max(1,N). +*> For optimum performance LWORK >= N*NB, where NB is the +*> optimal blocksize. +*> +*> If LWORK = -1, then a workspace query is assumed; the routine +*> only calculates the optimal size of the WORK array, returns +*> this value as the first entry of the WORK array, and no error +*> message related to LWORK is issued by XERBLA. +*> \endverbatim +*> +*> \param[out] INFO +*> \verbatim +*> INFO is INTEGER +*> = 0: successful exit +*> < 0: if INFO = -i, the i-th argument had an illegal value. +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2011 +* +*> \ingroup complex16GEcomputational +* +*> \par Further Details: +* ===================== +*> +*> \verbatim +*> +*> The matrix Q is represented as a product of (ihi-ilo) elementary +*> reflectors +*> +*> Q = H(ilo) H(ilo+1) . . . H(ihi-1). +*> +*> Each H(i) has the form +*> +*> H(i) = I - tau * v * v**H +*> +*> where tau is a complex scalar, and v is a complex vector with +*> v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on +*> exit in A(i+2:ihi,i), and tau in TAU(i). +*> +*> The contents of A are illustrated by the following example, with +*> n = 7, ilo = 2 and ihi = 6: +*> +*> on entry, on exit, +*> +*> ( a a a a a a a ) ( a a h h h h a ) +*> ( a a a a a a ) ( a h h h h a ) +*> ( a a a a a a ) ( h h h h h h ) +*> ( a a a a a a ) ( v2 h h h h h ) +*> ( a a a a a a ) ( v2 v3 h h h h ) +*> ( a a a a a a ) ( v2 v3 v4 h h h ) +*> ( a ) ( a ) +*> +*> where a denotes an element of the original matrix A, h denotes a +*> modified element of the upper Hessenberg matrix H, and vi denotes an +*> element of the vector defining H(i). +*> +*> This file is a slight modification of LAPACK-3.0's DGEHRD +*> subroutine incorporating improvements proposed by Quintana-Orti and +*> Van de Geijn (2006). (See DLAHR2.) +*> \endverbatim +*> +* ===================================================================== SUBROUTINE ZGEHRD( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO ) * -* -- LAPACK routine (version 3.3.1) -- +* -- LAPACK computational routine (version 3.4.0) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- -* -- April 2009 -- +* November 2011 * * .. Scalar Arguments .. INTEGER IHI, ILO, INFO, LDA, LWORK, N @@ -12,96 +180,6 @@ COMPLEX*16 A( LDA, * ), TAU( * ), WORK( * ) * .. * -* Purpose -* ======= -* -* ZGEHRD reduces a complex general matrix A to upper Hessenberg form H by -* an unitary similarity transformation: Q**H * A * Q = H . -* -* Arguments -* ========= -* -* N (input) INTEGER -* The order of the matrix A. N >= 0. -* -* ILO (input) INTEGER -* IHI (input) INTEGER -* It is assumed that A is already upper triangular in rows -* and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally -* set by a previous call to ZGEBAL; otherwise they should be -* set to 1 and N respectively. See Further Details. -* 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. -* -* A (input/output) COMPLEX*16 array, dimension (LDA,N) -* On entry, the N-by-N general matrix to be reduced. -* On exit, the upper triangle and the first subdiagonal of A -* are overwritten with the upper Hessenberg matrix H, and the -* elements below the first subdiagonal, with the array TAU, -* represent the unitary matrix Q as a product of elementary -* reflectors. See Further Details. -* -* LDA (input) INTEGER -* The leading dimension of the array A. LDA >= max(1,N). -* -* TAU (output) COMPLEX*16 array, dimension (N-1) -* The scalar factors of the elementary reflectors (see Further -* Details). Elements 1:ILO-1 and IHI:N-1 of TAU are set to -* zero. -* -* WORK (workspace/output) COMPLEX*16 array, dimension (LWORK) -* On exit, if INFO = 0, WORK(1) returns the optimal LWORK. -* -* LWORK (input) INTEGER -* The length of the array WORK. LWORK >= max(1,N). -* For optimum performance LWORK >= N*NB, where NB is the -* optimal blocksize. -* -* If LWORK = -1, then a workspace query is assumed; the routine -* only calculates the optimal size of the WORK array, returns -* this value as the first entry of the WORK array, and no error -* message related to LWORK is issued by XERBLA. -* -* INFO (output) INTEGER -* = 0: successful exit -* < 0: if INFO = -i, the i-th argument had an illegal value. -* -* Further Details -* =============== -* -* The matrix Q is represented as a product of (ihi-ilo) elementary -* reflectors -* -* Q = H(ilo) H(ilo+1) . . . H(ihi-1). -* -* Each H(i) has the form -* -* H(i) = I - tau * v * v**H -* -* where tau is a complex scalar, and v is a complex vector with -* v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on -* exit in A(i+2:ihi,i), and tau in TAU(i). -* -* The contents of A are illustrated by the following example, with -* n = 7, ilo = 2 and ihi = 6: -* -* on entry, on exit, -* -* ( a a a a a a a ) ( a a h h h h a ) -* ( a a a a a a ) ( a h h h h a ) -* ( a a a a a a ) ( h h h h h h ) -* ( a a a a a a ) ( v2 h h h h h ) -* ( a a a a a a ) ( v2 v3 h h h h ) -* ( a a a a a a ) ( v2 v3 v4 h h h ) -* ( a ) ( a ) -* -* where a denotes an element of the original matrix A, h denotes a -* modified element of the upper Hessenberg matrix H, and vi denotes an -* element of the vector defining H(i). -* -* This file is a slight modification of LAPACK-3.0's DGEHRD -* subroutine incorporating improvements proposed by Quintana-Orti and -* Van de Geijn (2006). (See DLAHR2.) -* * ===================================================================== * * .. Parameters ..