![]() |
LAPACK
3.4.1
LAPACK: Linear Algebra PACKage
|
00001 *> \brief \b ZUPGTR 00002 * 00003 * =========== DOCUMENTATION =========== 00004 * 00005 * Online html documentation available at 00006 * http://www.netlib.org/lapack/explore-html/ 00007 * 00008 *> \htmlonly 00009 *> Download ZUPGTR + dependencies 00010 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zupgtr.f"> 00011 *> [TGZ]</a> 00012 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zupgtr.f"> 00013 *> [ZIP]</a> 00014 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zupgtr.f"> 00015 *> [TXT]</a> 00016 *> \endhtmlonly 00017 * 00018 * Definition: 00019 * =========== 00020 * 00021 * SUBROUTINE ZUPGTR( UPLO, N, AP, TAU, Q, LDQ, WORK, INFO ) 00022 * 00023 * .. Scalar Arguments .. 00024 * CHARACTER UPLO 00025 * INTEGER INFO, LDQ, N 00026 * .. 00027 * .. Array Arguments .. 00028 * COMPLEX*16 AP( * ), Q( LDQ, * ), TAU( * ), WORK( * ) 00029 * .. 00030 * 00031 * 00032 *> \par Purpose: 00033 * ============= 00034 *> 00035 *> \verbatim 00036 *> 00037 *> ZUPGTR generates a complex unitary matrix Q which is defined as the 00038 *> product of n-1 elementary reflectors H(i) of order n, as returned by 00039 *> ZHPTRD using packed storage: 00040 *> 00041 *> if UPLO = 'U', Q = H(n-1) . . . H(2) H(1), 00042 *> 00043 *> if UPLO = 'L', Q = H(1) H(2) . . . H(n-1). 00044 *> \endverbatim 00045 * 00046 * Arguments: 00047 * ========== 00048 * 00049 *> \param[in] UPLO 00050 *> \verbatim 00051 *> UPLO is CHARACTER*1 00052 *> = 'U': Upper triangular packed storage used in previous 00053 *> call to ZHPTRD; 00054 *> = 'L': Lower triangular packed storage used in previous 00055 *> call to ZHPTRD. 00056 *> \endverbatim 00057 *> 00058 *> \param[in] N 00059 *> \verbatim 00060 *> N is INTEGER 00061 *> The order of the matrix Q. N >= 0. 00062 *> \endverbatim 00063 *> 00064 *> \param[in] AP 00065 *> \verbatim 00066 *> AP is COMPLEX*16 array, dimension (N*(N+1)/2) 00067 *> The vectors which define the elementary reflectors, as 00068 *> returned by ZHPTRD. 00069 *> \endverbatim 00070 *> 00071 *> \param[in] TAU 00072 *> \verbatim 00073 *> TAU is COMPLEX*16 array, dimension (N-1) 00074 *> TAU(i) must contain the scalar factor of the elementary 00075 *> reflector H(i), as returned by ZHPTRD. 00076 *> \endverbatim 00077 *> 00078 *> \param[out] Q 00079 *> \verbatim 00080 *> Q is COMPLEX*16 array, dimension (LDQ,N) 00081 *> The N-by-N unitary matrix Q. 00082 *> \endverbatim 00083 *> 00084 *> \param[in] LDQ 00085 *> \verbatim 00086 *> LDQ is INTEGER 00087 *> The leading dimension of the array Q. LDQ >= max(1,N). 00088 *> \endverbatim 00089 *> 00090 *> \param[out] WORK 00091 *> \verbatim 00092 *> WORK is COMPLEX*16 array, dimension (N-1) 00093 *> \endverbatim 00094 *> 00095 *> \param[out] INFO 00096 *> \verbatim 00097 *> INFO is INTEGER 00098 *> = 0: successful exit 00099 *> < 0: if INFO = -i, the i-th argument had an illegal value 00100 *> \endverbatim 00101 * 00102 * Authors: 00103 * ======== 00104 * 00105 *> \author Univ. of Tennessee 00106 *> \author Univ. of California Berkeley 00107 *> \author Univ. of Colorado Denver 00108 *> \author NAG Ltd. 00109 * 00110 *> \date November 2011 00111 * 00112 *> \ingroup complex16OTHERcomputational 00113 * 00114 * ===================================================================== 00115 SUBROUTINE ZUPGTR( UPLO, N, AP, TAU, Q, LDQ, WORK, INFO ) 00116 * 00117 * -- LAPACK computational routine (version 3.4.0) -- 00118 * -- LAPACK is a software package provided by Univ. of Tennessee, -- 00119 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 00120 * November 2011 00121 * 00122 * .. Scalar Arguments .. 00123 CHARACTER UPLO 00124 INTEGER INFO, LDQ, N 00125 * .. 00126 * .. Array Arguments .. 00127 COMPLEX*16 AP( * ), Q( LDQ, * ), TAU( * ), WORK( * ) 00128 * .. 00129 * 00130 * ===================================================================== 00131 * 00132 * .. Parameters .. 00133 COMPLEX*16 CZERO, CONE 00134 PARAMETER ( CZERO = ( 0.0D+0, 0.0D+0 ), 00135 $ CONE = ( 1.0D+0, 0.0D+0 ) ) 00136 * .. 00137 * .. Local Scalars .. 00138 LOGICAL UPPER 00139 INTEGER I, IINFO, IJ, J 00140 * .. 00141 * .. External Functions .. 00142 LOGICAL LSAME 00143 EXTERNAL LSAME 00144 * .. 00145 * .. External Subroutines .. 00146 EXTERNAL XERBLA, ZUNG2L, ZUNG2R 00147 * .. 00148 * .. Intrinsic Functions .. 00149 INTRINSIC MAX 00150 * .. 00151 * .. Executable Statements .. 00152 * 00153 * Test the input arguments 00154 * 00155 INFO = 0 00156 UPPER = LSAME( UPLO, 'U' ) 00157 IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN 00158 INFO = -1 00159 ELSE IF( N.LT.0 ) THEN 00160 INFO = -2 00161 ELSE IF( LDQ.LT.MAX( 1, N ) ) THEN 00162 INFO = -6 00163 END IF 00164 IF( INFO.NE.0 ) THEN 00165 CALL XERBLA( 'ZUPGTR', -INFO ) 00166 RETURN 00167 END IF 00168 * 00169 * Quick return if possible 00170 * 00171 IF( N.EQ.0 ) 00172 $ RETURN 00173 * 00174 IF( UPPER ) THEN 00175 * 00176 * Q was determined by a call to ZHPTRD with UPLO = 'U' 00177 * 00178 * Unpack the vectors which define the elementary reflectors and 00179 * set the last row and column of Q equal to those of the unit 00180 * matrix 00181 * 00182 IJ = 2 00183 DO 20 J = 1, N - 1 00184 DO 10 I = 1, J - 1 00185 Q( I, J ) = AP( IJ ) 00186 IJ = IJ + 1 00187 10 CONTINUE 00188 IJ = IJ + 2 00189 Q( N, J ) = CZERO 00190 20 CONTINUE 00191 DO 30 I = 1, N - 1 00192 Q( I, N ) = CZERO 00193 30 CONTINUE 00194 Q( N, N ) = CONE 00195 * 00196 * Generate Q(1:n-1,1:n-1) 00197 * 00198 CALL ZUNG2L( N-1, N-1, N-1, Q, LDQ, TAU, WORK, IINFO ) 00199 * 00200 ELSE 00201 * 00202 * Q was determined by a call to ZHPTRD with UPLO = 'L'. 00203 * 00204 * Unpack the vectors which define the elementary reflectors and 00205 * set the first row and column of Q equal to those of the unit 00206 * matrix 00207 * 00208 Q( 1, 1 ) = CONE 00209 DO 40 I = 2, N 00210 Q( I, 1 ) = CZERO 00211 40 CONTINUE 00212 IJ = 3 00213 DO 60 J = 2, N 00214 Q( 1, J ) = CZERO 00215 DO 50 I = J + 1, N 00216 Q( I, J ) = AP( IJ ) 00217 IJ = IJ + 1 00218 50 CONTINUE 00219 IJ = IJ + 2 00220 60 CONTINUE 00221 IF( N.GT.1 ) THEN 00222 * 00223 * Generate Q(2:n,2:n) 00224 * 00225 CALL ZUNG2R( N-1, N-1, N-1, Q( 2, 2 ), LDQ, TAU, WORK, 00226 $ IINFO ) 00227 END IF 00228 END IF 00229 RETURN 00230 * 00231 * End of ZUPGTR 00232 * 00233 END