LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
ctpmv.f
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00001 *> \brief \b CTPMV
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *  Definition:
00009 *  ===========
00010 *
00011 *       SUBROUTINE CTPMV(UPLO,TRANS,DIAG,N,AP,X,INCX)
00012 * 
00013 *       .. Scalar Arguments ..
00014 *       INTEGER INCX,N
00015 *       CHARACTER DIAG,TRANS,UPLO
00016 *       ..
00017 *       .. Array Arguments ..
00018 *       COMPLEX AP(*),X(*)
00019 *       ..
00020 *  
00021 *
00022 *> \par Purpose:
00023 *  =============
00024 *>
00025 *> \verbatim
00026 *>
00027 *> CTPMV  performs one of the matrix-vector operations
00028 *>
00029 *>    x := A*x,   or   x := A**T*x,   or   x := A**H*x,
00030 *>
00031 *> where x is an n element vector and  A is an n by n unit, or non-unit,
00032 *> upper or lower triangular matrix, supplied in packed form.
00033 *> \endverbatim
00034 *
00035 *  Arguments:
00036 *  ==========
00037 *
00038 *> \param[in] UPLO
00039 *> \verbatim
00040 *>          UPLO is CHARACTER*1
00041 *>           On entry, UPLO specifies whether the matrix is an upper or
00042 *>           lower triangular matrix as follows:
00043 *>
00044 *>              UPLO = 'U' or 'u'   A is an upper triangular matrix.
00045 *>
00046 *>              UPLO = 'L' or 'l'   A is a lower triangular matrix.
00047 *> \endverbatim
00048 *>
00049 *> \param[in] TRANS
00050 *> \verbatim
00051 *>          TRANS is CHARACTER*1
00052 *>           On entry, TRANS specifies the operation to be performed as
00053 *>           follows:
00054 *>
00055 *>              TRANS = 'N' or 'n'   x := A*x.
00056 *>
00057 *>              TRANS = 'T' or 't'   x := A**T*x.
00058 *>
00059 *>              TRANS = 'C' or 'c'   x := A**H*x.
00060 *> \endverbatim
00061 *>
00062 *> \param[in] DIAG
00063 *> \verbatim
00064 *>          DIAG is CHARACTER*1
00065 *>           On entry, DIAG specifies whether or not A is unit
00066 *>           triangular as follows:
00067 *>
00068 *>              DIAG = 'U' or 'u'   A is assumed to be unit triangular.
00069 *>
00070 *>              DIAG = 'N' or 'n'   A is not assumed to be unit
00071 *>                                  triangular.
00072 *> \endverbatim
00073 *>
00074 *> \param[in] N
00075 *> \verbatim
00076 *>          N is INTEGER
00077 *>           On entry, N specifies the order of the matrix A.
00078 *>           N must be at least zero.
00079 *> \endverbatim
00080 *>
00081 *> \param[in] AP
00082 *> \verbatim
00083 *>          AP is COMPLEX array of DIMENSION at least
00084 *>           ( ( n*( n + 1 ) )/2 ).
00085 *>           Before entry with  UPLO = 'U' or 'u', the array AP must
00086 *>           contain the upper triangular matrix packed sequentially,
00087 *>           column by column, so that AP( 1 ) contains a( 1, 1 ),
00088 *>           AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 )
00089 *>           respectively, and so on.
00090 *>           Before entry with UPLO = 'L' or 'l', the array AP must
00091 *>           contain the lower triangular matrix packed sequentially,
00092 *>           column by column, so that AP( 1 ) contains a( 1, 1 ),
00093 *>           AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 )
00094 *>           respectively, and so on.
00095 *>           Note that when  DIAG = 'U' or 'u', the diagonal elements of
00096 *>           A are not referenced, but are assumed to be unity.
00097 *> \endverbatim
00098 *>
00099 *> \param[in,out] X
00100 *> \verbatim
00101 *>          X is COMPLEX array of dimension at least
00102 *>           ( 1 + ( n - 1 )*abs( INCX ) ).
00103 *>           Before entry, the incremented array X must contain the n
00104 *>           element vector x. On exit, X is overwritten with the
00105 *>           tranformed vector x.
00106 *> \endverbatim
00107 *>
00108 *> \param[in] INCX
00109 *> \verbatim
00110 *>          INCX is INTEGER
00111 *>           On entry, INCX specifies the increment for the elements of
00112 *>           X. INCX must not be zero.
00113 *> \endverbatim
00114 *
00115 *  Authors:
00116 *  ========
00117 *
00118 *> \author Univ. of Tennessee 
00119 *> \author Univ. of California Berkeley 
00120 *> \author Univ. of Colorado Denver 
00121 *> \author NAG Ltd. 
00122 *
00123 *> \date November 2011
00124 *
00125 *> \ingroup complex_blas_level2
00126 *
00127 *> \par Further Details:
00128 *  =====================
00129 *>
00130 *> \verbatim
00131 *>
00132 *>  Level 2 Blas routine.
00133 *>  The vector and matrix arguments are not referenced when N = 0, or M = 0
00134 *>
00135 *>  -- Written on 22-October-1986.
00136 *>     Jack Dongarra, Argonne National Lab.
00137 *>     Jeremy Du Croz, Nag Central Office.
00138 *>     Sven Hammarling, Nag Central Office.
00139 *>     Richard Hanson, Sandia National Labs.
00140 *> \endverbatim
00141 *>
00142 *  =====================================================================
00143       SUBROUTINE CTPMV(UPLO,TRANS,DIAG,N,AP,X,INCX)
00144 *
00145 *  -- Reference BLAS level2 routine (version 3.4.0) --
00146 *  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
00147 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00148 *     November 2011
00149 *
00150 *     .. Scalar Arguments ..
00151       INTEGER INCX,N
00152       CHARACTER DIAG,TRANS,UPLO
00153 *     ..
00154 *     .. Array Arguments ..
00155       COMPLEX AP(*),X(*)
00156 *     ..
00157 *
00158 *  =====================================================================
00159 *
00160 *     .. Parameters ..
00161       COMPLEX ZERO
00162       PARAMETER (ZERO= (0.0E+0,0.0E+0))
00163 *     ..
00164 *     .. Local Scalars ..
00165       COMPLEX TEMP
00166       INTEGER I,INFO,IX,J,JX,K,KK,KX
00167       LOGICAL NOCONJ,NOUNIT
00168 *     ..
00169 *     .. External Functions ..
00170       LOGICAL LSAME
00171       EXTERNAL LSAME
00172 *     ..
00173 *     .. External Subroutines ..
00174       EXTERNAL XERBLA
00175 *     ..
00176 *     .. Intrinsic Functions ..
00177       INTRINSIC CONJG
00178 *     ..
00179 *
00180 *     Test the input parameters.
00181 *
00182       INFO = 0
00183       IF (.NOT.LSAME(UPLO,'U') .AND. .NOT.LSAME(UPLO,'L')) THEN
00184           INFO = 1
00185       ELSE IF (.NOT.LSAME(TRANS,'N') .AND. .NOT.LSAME(TRANS,'T') .AND.
00186      +         .NOT.LSAME(TRANS,'C')) THEN
00187           INFO = 2
00188       ELSE IF (.NOT.LSAME(DIAG,'U') .AND. .NOT.LSAME(DIAG,'N')) THEN
00189           INFO = 3
00190       ELSE IF (N.LT.0) THEN
00191           INFO = 4
00192       ELSE IF (INCX.EQ.0) THEN
00193           INFO = 7
00194       END IF
00195       IF (INFO.NE.0) THEN
00196           CALL XERBLA('CTPMV ',INFO)
00197           RETURN
00198       END IF
00199 *
00200 *     Quick return if possible.
00201 *
00202       IF (N.EQ.0) RETURN
00203 *
00204       NOCONJ = LSAME(TRANS,'T')
00205       NOUNIT = LSAME(DIAG,'N')
00206 *
00207 *     Set up the start point in X if the increment is not unity. This
00208 *     will be  ( N - 1 )*INCX  too small for descending loops.
00209 *
00210       IF (INCX.LE.0) THEN
00211           KX = 1 - (N-1)*INCX
00212       ELSE IF (INCX.NE.1) THEN
00213           KX = 1
00214       END IF
00215 *
00216 *     Start the operations. In this version the elements of AP are
00217 *     accessed sequentially with one pass through AP.
00218 *
00219       IF (LSAME(TRANS,'N')) THEN
00220 *
00221 *        Form  x:= A*x.
00222 *
00223           IF (LSAME(UPLO,'U')) THEN
00224               KK = 1
00225               IF (INCX.EQ.1) THEN
00226                   DO 20 J = 1,N
00227                       IF (X(J).NE.ZERO) THEN
00228                           TEMP = X(J)
00229                           K = KK
00230                           DO 10 I = 1,J - 1
00231                               X(I) = X(I) + TEMP*AP(K)
00232                               K = K + 1
00233    10                     CONTINUE
00234                           IF (NOUNIT) X(J) = X(J)*AP(KK+J-1)
00235                       END IF
00236                       KK = KK + J
00237    20             CONTINUE
00238               ELSE
00239                   JX = KX
00240                   DO 40 J = 1,N
00241                       IF (X(JX).NE.ZERO) THEN
00242                           TEMP = X(JX)
00243                           IX = KX
00244                           DO 30 K = KK,KK + J - 2
00245                               X(IX) = X(IX) + TEMP*AP(K)
00246                               IX = IX + INCX
00247    30                     CONTINUE
00248                           IF (NOUNIT) X(JX) = X(JX)*AP(KK+J-1)
00249                       END IF
00250                       JX = JX + INCX
00251                       KK = KK + J
00252    40             CONTINUE
00253               END IF
00254           ELSE
00255               KK = (N* (N+1))/2
00256               IF (INCX.EQ.1) THEN
00257                   DO 60 J = N,1,-1
00258                       IF (X(J).NE.ZERO) THEN
00259                           TEMP = X(J)
00260                           K = KK
00261                           DO 50 I = N,J + 1,-1
00262                               X(I) = X(I) + TEMP*AP(K)
00263                               K = K - 1
00264    50                     CONTINUE
00265                           IF (NOUNIT) X(J) = X(J)*AP(KK-N+J)
00266                       END IF
00267                       KK = KK - (N-J+1)
00268    60             CONTINUE
00269               ELSE
00270                   KX = KX + (N-1)*INCX
00271                   JX = KX
00272                   DO 80 J = N,1,-1
00273                       IF (X(JX).NE.ZERO) THEN
00274                           TEMP = X(JX)
00275                           IX = KX
00276                           DO 70 K = KK,KK - (N- (J+1)),-1
00277                               X(IX) = X(IX) + TEMP*AP(K)
00278                               IX = IX - INCX
00279    70                     CONTINUE
00280                           IF (NOUNIT) X(JX) = X(JX)*AP(KK-N+J)
00281                       END IF
00282                       JX = JX - INCX
00283                       KK = KK - (N-J+1)
00284    80             CONTINUE
00285               END IF
00286           END IF
00287       ELSE
00288 *
00289 *        Form  x := A**T*x  or  x := A**H*x.
00290 *
00291           IF (LSAME(UPLO,'U')) THEN
00292               KK = (N* (N+1))/2
00293               IF (INCX.EQ.1) THEN
00294                   DO 110 J = N,1,-1
00295                       TEMP = X(J)
00296                       K = KK - 1
00297                       IF (NOCONJ) THEN
00298                           IF (NOUNIT) TEMP = TEMP*AP(KK)
00299                           DO 90 I = J - 1,1,-1
00300                               TEMP = TEMP + AP(K)*X(I)
00301                               K = K - 1
00302    90                     CONTINUE
00303                       ELSE
00304                           IF (NOUNIT) TEMP = TEMP*CONJG(AP(KK))
00305                           DO 100 I = J - 1,1,-1
00306                               TEMP = TEMP + CONJG(AP(K))*X(I)
00307                               K = K - 1
00308   100                     CONTINUE
00309                       END IF
00310                       X(J) = TEMP
00311                       KK = KK - J
00312   110             CONTINUE
00313               ELSE
00314                   JX = KX + (N-1)*INCX
00315                   DO 140 J = N,1,-1
00316                       TEMP = X(JX)
00317                       IX = JX
00318                       IF (NOCONJ) THEN
00319                           IF (NOUNIT) TEMP = TEMP*AP(KK)
00320                           DO 120 K = KK - 1,KK - J + 1,-1
00321                               IX = IX - INCX
00322                               TEMP = TEMP + AP(K)*X(IX)
00323   120                     CONTINUE
00324                       ELSE
00325                           IF (NOUNIT) TEMP = TEMP*CONJG(AP(KK))
00326                           DO 130 K = KK - 1,KK - J + 1,-1
00327                               IX = IX - INCX
00328                               TEMP = TEMP + CONJG(AP(K))*X(IX)
00329   130                     CONTINUE
00330                       END IF
00331                       X(JX) = TEMP
00332                       JX = JX - INCX
00333                       KK = KK - J
00334   140             CONTINUE
00335               END IF
00336           ELSE
00337               KK = 1
00338               IF (INCX.EQ.1) THEN
00339                   DO 170 J = 1,N
00340                       TEMP = X(J)
00341                       K = KK + 1
00342                       IF (NOCONJ) THEN
00343                           IF (NOUNIT) TEMP = TEMP*AP(KK)
00344                           DO 150 I = J + 1,N
00345                               TEMP = TEMP + AP(K)*X(I)
00346                               K = K + 1
00347   150                     CONTINUE
00348                       ELSE
00349                           IF (NOUNIT) TEMP = TEMP*CONJG(AP(KK))
00350                           DO 160 I = J + 1,N
00351                               TEMP = TEMP + CONJG(AP(K))*X(I)
00352                               K = K + 1
00353   160                     CONTINUE
00354                       END IF
00355                       X(J) = TEMP
00356                       KK = KK + (N-J+1)
00357   170             CONTINUE
00358               ELSE
00359                   JX = KX
00360                   DO 200 J = 1,N
00361                       TEMP = X(JX)
00362                       IX = JX
00363                       IF (NOCONJ) THEN
00364                           IF (NOUNIT) TEMP = TEMP*AP(KK)
00365                           DO 180 K = KK + 1,KK + N - J
00366                               IX = IX + INCX
00367                               TEMP = TEMP + AP(K)*X(IX)
00368   180                     CONTINUE
00369                       ELSE
00370                           IF (NOUNIT) TEMP = TEMP*CONJG(AP(KK))
00371                           DO 190 K = KK + 1,KK + N - J
00372                               IX = IX + INCX
00373                               TEMP = TEMP + CONJG(AP(K))*X(IX)
00374   190                     CONTINUE
00375                       END IF
00376                       X(JX) = TEMP
00377                       JX = JX + INCX
00378                       KK = KK + (N-J+1)
00379   200             CONTINUE
00380               END IF
00381           END IF
00382       END IF
00383 *
00384       RETURN
00385 *
00386 *     End of CTPMV .
00387 *
00388       END
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