File:  [local] / rpl / lapack / lapack / zunmr3.f
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Sat Aug 7 13:22:47 2010 UTC (14 years, 2 months ago) by bertrand
Branches: MAIN
CVS tags: HEAD
Mise à jour globale de Lapack 3.2.2.

    1:       SUBROUTINE ZUNMR3( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
    2:      $                   WORK, INFO )
    3: *
    4: *  -- LAPACK routine (version 3.2) --
    5: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
    6: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
    7: *     November 2006
    8: *
    9: *     .. Scalar Arguments ..
   10:       CHARACTER          SIDE, TRANS
   11:       INTEGER            INFO, K, L, LDA, LDC, M, N
   12: *     ..
   13: *     .. Array Arguments ..
   14:       COMPLEX*16         A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
   15: *     ..
   16: *
   17: *  Purpose
   18: *  =======
   19: *
   20: *  ZUNMR3 overwrites the general complex m by n matrix C with
   21: *
   22: *        Q * C  if SIDE = 'L' and TRANS = 'N', or
   23: *
   24: *        Q'* C  if SIDE = 'L' and TRANS = 'C', or
   25: *
   26: *        C * Q  if SIDE = 'R' and TRANS = 'N', or
   27: *
   28: *        C * Q' if SIDE = 'R' and TRANS = 'C',
   29: *
   30: *  where Q is a complex unitary matrix defined as the product of k
   31: *  elementary reflectors
   32: *
   33: *        Q = H(1) H(2) . . . H(k)
   34: *
   35: *  as returned by ZTZRZF. Q is of order m if SIDE = 'L' and of order n
   36: *  if SIDE = 'R'.
   37: *
   38: *  Arguments
   39: *  =========
   40: *
   41: *  SIDE    (input) CHARACTER*1
   42: *          = 'L': apply Q or Q' from the Left
   43: *          = 'R': apply Q or Q' from the Right
   44: *
   45: *  TRANS   (input) CHARACTER*1
   46: *          = 'N': apply Q  (No transpose)
   47: *          = 'C': apply Q' (Conjugate transpose)
   48: *
   49: *  M       (input) INTEGER
   50: *          The number of rows of the matrix C. M >= 0.
   51: *
   52: *  N       (input) INTEGER
   53: *          The number of columns of the matrix C. N >= 0.
   54: *
   55: *  K       (input) INTEGER
   56: *          The number of elementary reflectors whose product defines
   57: *          the matrix Q.
   58: *          If SIDE = 'L', M >= K >= 0;
   59: *          if SIDE = 'R', N >= K >= 0.
   60: *
   61: *  L       (input) INTEGER
   62: *          The number of columns of the matrix A containing
   63: *          the meaningful part of the Householder reflectors.
   64: *          If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
   65: *
   66: *  A       (input) COMPLEX*16 array, dimension
   67: *                               (LDA,M) if SIDE = 'L',
   68: *                               (LDA,N) if SIDE = 'R'
   69: *          The i-th row must contain the vector which defines the
   70: *          elementary reflector H(i), for i = 1,2,...,k, as returned by
   71: *          ZTZRZF in the last k rows of its array argument A.
   72: *          A is modified by the routine but restored on exit.
   73: *
   74: *  LDA     (input) INTEGER
   75: *          The leading dimension of the array A. LDA >= max(1,K).
   76: *
   77: *  TAU     (input) COMPLEX*16 array, dimension (K)
   78: *          TAU(i) must contain the scalar factor of the elementary
   79: *          reflector H(i), as returned by ZTZRZF.
   80: *
   81: *  C       (input/output) COMPLEX*16 array, dimension (LDC,N)
   82: *          On entry, the m-by-n matrix C.
   83: *          On exit, C is overwritten by Q*C or Q'*C or C*Q' or C*Q.
   84: *
   85: *  LDC     (input) INTEGER
   86: *          The leading dimension of the array C. LDC >= max(1,M).
   87: *
   88: *  WORK    (workspace) COMPLEX*16 array, dimension
   89: *                                   (N) if SIDE = 'L',
   90: *                                   (M) if SIDE = 'R'
   91: *
   92: *  INFO    (output) INTEGER
   93: *          = 0: successful exit
   94: *          < 0: if INFO = -i, the i-th argument had an illegal value
   95: *
   96: *  Further Details
   97: *  ===============
   98: *
   99: *  Based on contributions by
  100: *    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
  101: *
  102: *  =====================================================================
  103: *
  104: *     .. Local Scalars ..
  105:       LOGICAL            LEFT, NOTRAN
  106:       INTEGER            I, I1, I2, I3, IC, JA, JC, MI, NI, NQ
  107:       COMPLEX*16         TAUI
  108: *     ..
  109: *     .. External Functions ..
  110:       LOGICAL            LSAME
  111:       EXTERNAL           LSAME
  112: *     ..
  113: *     .. External Subroutines ..
  114:       EXTERNAL           XERBLA, ZLARZ
  115: *     ..
  116: *     .. Intrinsic Functions ..
  117:       INTRINSIC          DCONJG, MAX
  118: *     ..
  119: *     .. Executable Statements ..
  120: *
  121: *     Test the input arguments
  122: *
  123:       INFO = 0
  124:       LEFT = LSAME( SIDE, 'L' )
  125:       NOTRAN = LSAME( TRANS, 'N' )
  126: *
  127: *     NQ is the order of Q
  128: *
  129:       IF( LEFT ) THEN
  130:          NQ = M
  131:       ELSE
  132:          NQ = N
  133:       END IF
  134:       IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
  135:          INFO = -1
  136:       ELSE IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
  137:          INFO = -2
  138:       ELSE IF( M.LT.0 ) THEN
  139:          INFO = -3
  140:       ELSE IF( N.LT.0 ) THEN
  141:          INFO = -4
  142:       ELSE IF( K.LT.0 .OR. K.GT.NQ ) THEN
  143:          INFO = -5
  144:       ELSE IF( L.LT.0 .OR. ( LEFT .AND. ( L.GT.M ) ) .OR.
  145:      $         ( .NOT.LEFT .AND. ( L.GT.N ) ) ) THEN
  146:          INFO = -6
  147:       ELSE IF( LDA.LT.MAX( 1, K ) ) THEN
  148:          INFO = -8
  149:       ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
  150:          INFO = -11
  151:       END IF
  152:       IF( INFO.NE.0 ) THEN
  153:          CALL XERBLA( 'ZUNMR3', -INFO )
  154:          RETURN
  155:       END IF
  156: *
  157: *     Quick return if possible
  158: *
  159:       IF( M.EQ.0 .OR. N.EQ.0 .OR. K.EQ.0 )
  160:      $   RETURN
  161: *
  162:       IF( ( LEFT .AND. .NOT.NOTRAN .OR. .NOT.LEFT .AND. NOTRAN ) ) THEN
  163:          I1 = 1
  164:          I2 = K
  165:          I3 = 1
  166:       ELSE
  167:          I1 = K
  168:          I2 = 1
  169:          I3 = -1
  170:       END IF
  171: *
  172:       IF( LEFT ) THEN
  173:          NI = N
  174:          JA = M - L + 1
  175:          JC = 1
  176:       ELSE
  177:          MI = M
  178:          JA = N - L + 1
  179:          IC = 1
  180:       END IF
  181: *
  182:       DO 10 I = I1, I2, I3
  183:          IF( LEFT ) THEN
  184: *
  185: *           H(i) or H(i)' is applied to C(i:m,1:n)
  186: *
  187:             MI = M - I + 1
  188:             IC = I
  189:          ELSE
  190: *
  191: *           H(i) or H(i)' is applied to C(1:m,i:n)
  192: *
  193:             NI = N - I + 1
  194:             JC = I
  195:          END IF
  196: *
  197: *        Apply H(i) or H(i)'
  198: *
  199:          IF( NOTRAN ) THEN
  200:             TAUI = TAU( I )
  201:          ELSE
  202:             TAUI = DCONJG( TAU( I ) )
  203:          END IF
  204:          CALL ZLARZ( SIDE, MI, NI, L, A( I, JA ), LDA, TAUI,
  205:      $               C( IC, JC ), LDC, WORK )
  206: *
  207:    10 CONTINUE
  208: *
  209:       RETURN
  210: *
  211: *     End of ZUNMR3
  212: *
  213:       END

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