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Patches pour OS/2

    1:       SUBROUTINE ZUNG2R( M, N, K, A, LDA, TAU, WORK, INFO )
    2: *
    3: *  -- LAPACK routine (version 3.2) --
    4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
    5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
    6: *     November 2006
    7: *
    8: *     .. Scalar Arguments ..
    9:       INTEGER            INFO, K, LDA, M, N
   10: *     ..
   11: *     .. Array Arguments ..
   12:       COMPLEX*16         A( LDA, * ), TAU( * ), WORK( * )
   13: *     ..
   14: *
   15: *  Purpose
   16: *  =======
   17: *
   18: *  ZUNG2R generates an m by n complex matrix Q with orthonormal columns,
   19: *  which is defined as the first n columns of a product of k elementary
   20: *  reflectors of order m
   21: *
   22: *        Q  =  H(1) H(2) . . . H(k)
   23: *
   24: *  as returned by ZGEQRF.
   25: *
   26: *  Arguments
   27: *  =========
   28: *
   29: *  M       (input) INTEGER
   30: *          The number of rows of the matrix Q. M >= 0.
   31: *
   32: *  N       (input) INTEGER
   33: *          The number of columns of the matrix Q. M >= N >= 0.
   34: *
   35: *  K       (input) INTEGER
   36: *          The number of elementary reflectors whose product defines the
   37: *          matrix Q. N >= K >= 0.
   38: *
   39: *  A       (input/output) COMPLEX*16 array, dimension (LDA,N)
   40: *          On entry, the i-th column must contain the vector which
   41: *          defines the elementary reflector H(i), for i = 1,2,...,k, as
   42: *          returned by ZGEQRF in the first k columns of its array
   43: *          argument A.
   44: *          On exit, the m by n matrix Q.
   45: *
   46: *  LDA     (input) INTEGER
   47: *          The first dimension of the array A. LDA >= max(1,M).
   48: *
   49: *  TAU     (input) COMPLEX*16 array, dimension (K)
   50: *          TAU(i) must contain the scalar factor of the elementary
   51: *          reflector H(i), as returned by ZGEQRF.
   52: *
   53: *  WORK    (workspace) COMPLEX*16 array, dimension (N)
   54: *
   55: *  INFO    (output) INTEGER
   56: *          = 0: successful exit
   57: *          < 0: if INFO = -i, the i-th argument has an illegal value
   58: *
   59: *  =====================================================================
   60: *
   61: *     .. Parameters ..
   62:       COMPLEX*16         ONE, ZERO
   63:       PARAMETER          ( ONE = ( 1.0D+0, 0.0D+0 ),
   64:      $                   ZERO = ( 0.0D+0, 0.0D+0 ) )
   65: *     ..
   66: *     .. Local Scalars ..
   67:       INTEGER            I, J, L
   68: *     ..
   69: *     .. External Subroutines ..
   70:       EXTERNAL           XERBLA, ZLARF, ZSCAL
   71: *     ..
   72: *     .. Intrinsic Functions ..
   73:       INTRINSIC          MAX
   74: *     ..
   75: *     .. Executable Statements ..
   76: *
   77: *     Test the input arguments
   78: *
   79:       INFO = 0
   80:       IF( M.LT.0 ) THEN
   81:          INFO = -1
   82:       ELSE IF( N.LT.0 .OR. N.GT.M ) THEN
   83:          INFO = -2
   84:       ELSE IF( K.LT.0 .OR. K.GT.N ) THEN
   85:          INFO = -3
   86:       ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
   87:          INFO = -5
   88:       END IF
   89:       IF( INFO.NE.0 ) THEN
   90:          CALL XERBLA( 'ZUNG2R', -INFO )
   91:          RETURN
   92:       END IF
   93: *
   94: *     Quick return if possible
   95: *
   96:       IF( N.LE.0 )
   97:      $   RETURN
   98: *
   99: *     Initialise columns k+1:n to columns of the unit matrix
  100: *
  101:       DO 20 J = K + 1, N
  102:          DO 10 L = 1, M
  103:             A( L, J ) = ZERO
  104:    10    CONTINUE
  105:          A( J, J ) = ONE
  106:    20 CONTINUE
  107: *
  108:       DO 40 I = K, 1, -1
  109: *
  110: *        Apply H(i) to A(i:m,i:n) from the left
  111: *
  112:          IF( I.LT.N ) THEN
  113:             A( I, I ) = ONE
  114:             CALL ZLARF( 'Left', M-I+1, N-I, A( I, I ), 1, TAU( I ),
  115:      $                  A( I, I+1 ), LDA, WORK )
  116:          END IF
  117:          IF( I.LT.M )
  118:      $      CALL ZSCAL( M-I, -TAU( I ), A( I+1, I ), 1 )
  119:          A( I, I ) = ONE - TAU( I )
  120: *
  121: *        Set A(1:i-1,i) to zero
  122: *
  123:          DO 30 L = 1, I - 1
  124:             A( L, I ) = ZERO
  125:    30    CONTINUE
  126:    40 CONTINUE
  127:       RETURN
  128: *
  129: *     End of ZUNG2R
  130: *
  131:       END