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LAPACK
3.4.1
LAPACK: Linear Algebra PACKage
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00001 *> \brief \b DLAUUM 00002 * 00003 * =========== DOCUMENTATION =========== 00004 * 00005 * Online html documentation available at 00006 * http://www.netlib.org/lapack/explore-html/ 00007 * 00008 *> \htmlonly 00009 *> Download DLAUUM + dependencies 00010 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlauum.f"> 00011 *> [TGZ]</a> 00012 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlauum.f"> 00013 *> [ZIP]</a> 00014 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlauum.f"> 00015 *> [TXT]</a> 00016 *> \endhtmlonly 00017 * 00018 * Definition: 00019 * =========== 00020 * 00021 * SUBROUTINE DLAUUM( UPLO, N, A, LDA, INFO ) 00022 * 00023 * .. Scalar Arguments .. 00024 * CHARACTER UPLO 00025 * INTEGER INFO, LDA, N 00026 * .. 00027 * .. Array Arguments .. 00028 * DOUBLE PRECISION A( LDA, * ) 00029 * .. 00030 * 00031 * 00032 *> \par Purpose: 00033 * ============= 00034 *> 00035 *> \verbatim 00036 *> 00037 *> DLAUUM computes the product U * U**T or L**T * L, where the triangular 00038 *> factor U or L is stored in the upper or lower triangular part of 00039 *> the array A. 00040 *> 00041 *> If UPLO = 'U' or 'u' then the upper triangle of the result is stored, 00042 *> overwriting the factor U in A. 00043 *> If UPLO = 'L' or 'l' then the lower triangle of the result is stored, 00044 *> overwriting the factor L in A. 00045 *> 00046 *> This is the blocked form of the algorithm, calling Level 3 BLAS. 00047 *> \endverbatim 00048 * 00049 * Arguments: 00050 * ========== 00051 * 00052 *> \param[in] UPLO 00053 *> \verbatim 00054 *> UPLO is CHARACTER*1 00055 *> Specifies whether the triangular factor stored in the array A 00056 *> is upper or lower triangular: 00057 *> = 'U': Upper triangular 00058 *> = 'L': Lower triangular 00059 *> \endverbatim 00060 *> 00061 *> \param[in] N 00062 *> \verbatim 00063 *> N is INTEGER 00064 *> The order of the triangular factor U or L. N >= 0. 00065 *> \endverbatim 00066 *> 00067 *> \param[in,out] A 00068 *> \verbatim 00069 *> A is DOUBLE PRECISION array, dimension (LDA,N) 00070 *> On entry, the triangular factor U or L. 00071 *> On exit, if UPLO = 'U', the upper triangle of A is 00072 *> overwritten with the upper triangle of the product U * U**T; 00073 *> if UPLO = 'L', the lower triangle of A is overwritten with 00074 *> the lower triangle of the product L**T * L. 00075 *> \endverbatim 00076 *> 00077 *> \param[in] LDA 00078 *> \verbatim 00079 *> LDA is INTEGER 00080 *> The leading dimension of the array A. LDA >= max(1,N). 00081 *> \endverbatim 00082 *> 00083 *> \param[out] INFO 00084 *> \verbatim 00085 *> INFO is INTEGER 00086 *> = 0: successful exit 00087 *> < 0: if INFO = -k, the k-th argument had an illegal value 00088 *> \endverbatim 00089 * 00090 * Authors: 00091 * ======== 00092 * 00093 *> \author Univ. of Tennessee 00094 *> \author Univ. of California Berkeley 00095 *> \author Univ. of Colorado Denver 00096 *> \author NAG Ltd. 00097 * 00098 *> \date November 2011 00099 * 00100 *> \ingroup doubleOTHERauxiliary 00101 * 00102 * ===================================================================== 00103 SUBROUTINE DLAUUM( UPLO, N, A, LDA, INFO ) 00104 * 00105 * -- LAPACK auxiliary routine (version 3.4.0) -- 00106 * -- LAPACK is a software package provided by Univ. of Tennessee, -- 00107 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 00108 * November 2011 00109 * 00110 * .. Scalar Arguments .. 00111 CHARACTER UPLO 00112 INTEGER INFO, LDA, N 00113 * .. 00114 * .. Array Arguments .. 00115 DOUBLE PRECISION A( LDA, * ) 00116 * .. 00117 * 00118 * ===================================================================== 00119 * 00120 * .. Parameters .. 00121 DOUBLE PRECISION ONE 00122 PARAMETER ( ONE = 1.0D+0 ) 00123 * .. 00124 * .. Local Scalars .. 00125 LOGICAL UPPER 00126 INTEGER I, IB, NB 00127 * .. 00128 * .. External Functions .. 00129 LOGICAL LSAME 00130 INTEGER ILAENV 00131 EXTERNAL LSAME, ILAENV 00132 * .. 00133 * .. External Subroutines .. 00134 EXTERNAL DGEMM, DLAUU2, DSYRK, DTRMM, XERBLA 00135 * .. 00136 * .. Intrinsic Functions .. 00137 INTRINSIC MAX, MIN 00138 * .. 00139 * .. Executable Statements .. 00140 * 00141 * Test the input parameters. 00142 * 00143 INFO = 0 00144 UPPER = LSAME( UPLO, 'U' ) 00145 IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN 00146 INFO = -1 00147 ELSE IF( N.LT.0 ) THEN 00148 INFO = -2 00149 ELSE IF( LDA.LT.MAX( 1, N ) ) THEN 00150 INFO = -4 00151 END IF 00152 IF( INFO.NE.0 ) THEN 00153 CALL XERBLA( 'DLAUUM', -INFO ) 00154 RETURN 00155 END IF 00156 * 00157 * Quick return if possible 00158 * 00159 IF( N.EQ.0 ) 00160 $ RETURN 00161 * 00162 * Determine the block size for this environment. 00163 * 00164 NB = ILAENV( 1, 'DLAUUM', UPLO, N, -1, -1, -1 ) 00165 * 00166 IF( NB.LE.1 .OR. NB.GE.N ) THEN 00167 * 00168 * Use unblocked code 00169 * 00170 CALL DLAUU2( UPLO, N, A, LDA, INFO ) 00171 ELSE 00172 * 00173 * Use blocked code 00174 * 00175 IF( UPPER ) THEN 00176 * 00177 * Compute the product U * U**T. 00178 * 00179 DO 10 I = 1, N, NB 00180 IB = MIN( NB, N-I+1 ) 00181 CALL DTRMM( 'Right', 'Upper', 'Transpose', 'Non-unit', 00182 $ I-1, IB, ONE, A( I, I ), LDA, A( 1, I ), 00183 $ LDA ) 00184 CALL DLAUU2( 'Upper', IB, A( I, I ), LDA, INFO ) 00185 IF( I+IB.LE.N ) THEN 00186 CALL DGEMM( 'No transpose', 'Transpose', I-1, IB, 00187 $ N-I-IB+1, ONE, A( 1, I+IB ), LDA, 00188 $ A( I, I+IB ), LDA, ONE, A( 1, I ), LDA ) 00189 CALL DSYRK( 'Upper', 'No transpose', IB, N-I-IB+1, 00190 $ ONE, A( I, I+IB ), LDA, ONE, A( I, I ), 00191 $ LDA ) 00192 END IF 00193 10 CONTINUE 00194 ELSE 00195 * 00196 * Compute the product L**T * L. 00197 * 00198 DO 20 I = 1, N, NB 00199 IB = MIN( NB, N-I+1 ) 00200 CALL DTRMM( 'Left', 'Lower', 'Transpose', 'Non-unit', IB, 00201 $ I-1, ONE, A( I, I ), LDA, A( I, 1 ), LDA ) 00202 CALL DLAUU2( 'Lower', IB, A( I, I ), LDA, INFO ) 00203 IF( I+IB.LE.N ) THEN 00204 CALL DGEMM( 'Transpose', 'No transpose', IB, I-1, 00205 $ N-I-IB+1, ONE, A( I+IB, I ), LDA, 00206 $ A( I+IB, 1 ), LDA, ONE, A( I, 1 ), LDA ) 00207 CALL DSYRK( 'Lower', 'Transpose', IB, N-I-IB+1, ONE, 00208 $ A( I+IB, I ), LDA, ONE, A( I, I ), LDA ) 00209 END IF 00210 20 CONTINUE 00211 END IF 00212 END IF 00213 * 00214 RETURN 00215 * 00216 * End of DLAUUM 00217 * 00218 END