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Patches pour OS/2

    1:       SUBROUTINE DORGL2( 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:       DOUBLE PRECISION   A( LDA, * ), TAU( * ), WORK( * )
   13: *     ..
   14: *
   15: *  Purpose
   16: *  =======
   17: *
   18: *  DORGL2 generates an m by n real matrix Q with orthonormal rows,
   19: *  which is defined as the first m rows of a product of k elementary
   20: *  reflectors of order n
   21: *
   22: *        Q  =  H(k) . . . H(2) H(1)
   23: *
   24: *  as returned by DGELQF.
   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. N >= M.
   34: *
   35: *  K       (input) INTEGER
   36: *          The number of elementary reflectors whose product defines the
   37: *          matrix Q. M >= K >= 0.
   38: *
   39: *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
   40: *          On entry, the i-th row must contain the vector which defines
   41: *          the elementary reflector H(i), for i = 1,2,...,k, as returned
   42: *          by DGELQF in the first k rows of its array argument A.
   43: *          On exit, the m-by-n matrix Q.
   44: *
   45: *  LDA     (input) INTEGER
   46: *          The first dimension of the array A. LDA >= max(1,M).
   47: *
   48: *  TAU     (input) DOUBLE PRECISION array, dimension (K)
   49: *          TAU(i) must contain the scalar factor of the elementary
   50: *          reflector H(i), as returned by DGELQF.
   51: *
   52: *  WORK    (workspace) DOUBLE PRECISION array, dimension (M)
   53: *
   54: *  INFO    (output) INTEGER
   55: *          = 0: successful exit
   56: *          < 0: if INFO = -i, the i-th argument has an illegal value
   57: *
   58: *  =====================================================================
   59: *
   60: *     .. Parameters ..
   61:       DOUBLE PRECISION   ONE, ZERO
   62:       PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
   63: *     ..
   64: *     .. Local Scalars ..
   65:       INTEGER            I, J, L
   66: *     ..
   67: *     .. External Subroutines ..
   68:       EXTERNAL           DLARF, DSCAL, XERBLA
   69: *     ..
   70: *     .. Intrinsic Functions ..
   71:       INTRINSIC          MAX
   72: *     ..
   73: *     .. Executable Statements ..
   74: *
   75: *     Test the input arguments
   76: *
   77:       INFO = 0
   78:       IF( M.LT.0 ) THEN
   79:          INFO = -1
   80:       ELSE IF( N.LT.M ) THEN
   81:          INFO = -2
   82:       ELSE IF( K.LT.0 .OR. K.GT.M ) THEN
   83:          INFO = -3
   84:       ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
   85:          INFO = -5
   86:       END IF
   87:       IF( INFO.NE.0 ) THEN
   88:          CALL XERBLA( 'DORGL2', -INFO )
   89:          RETURN
   90:       END IF
   91: *
   92: *     Quick return if possible
   93: *
   94:       IF( M.LE.0 )
   95:      $   RETURN
   96: *
   97:       IF( K.LT.M ) THEN
   98: *
   99: *        Initialise rows k+1:m to rows of the unit matrix
  100: *
  101:          DO 20 J = 1, N
  102:             DO 10 L = K + 1, M
  103:                A( L, J ) = ZERO
  104:    10       CONTINUE
  105:             IF( J.GT.K .AND. J.LE.M )
  106:      $         A( J, J ) = ONE
  107:    20    CONTINUE
  108:       END IF
  109: *
  110:       DO 40 I = K, 1, -1
  111: *
  112: *        Apply H(i) to A(i:m,i:n) from the right
  113: *
  114:          IF( I.LT.N ) THEN
  115:             IF( I.LT.M ) THEN
  116:                A( I, I ) = ONE
  117:                CALL DLARF( 'Right', M-I, N-I+1, A( I, I ), LDA,
  118:      $                     TAU( I ), A( I+1, I ), LDA, WORK )
  119:             END IF
  120:             CALL DSCAL( N-I, -TAU( I ), A( I, I+1 ), LDA )
  121:          END IF
  122:          A( I, I ) = ONE - TAU( I )
  123: *
  124: *        Set A(i,1:i-1) to zero
  125: *
  126:          DO 30 L = 1, I - 1
  127:             A( I, L ) = ZERO
  128:    30    CONTINUE
  129:    40 CONTINUE
  130:       RETURN
  131: *
  132: *     End of DORGL2
  133: *
  134:       END