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Patches pour OS/2

    1:       SUBROUTINE ZPPTRI( UPLO, N, AP, 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:       CHARACTER          UPLO
   10:       INTEGER            INFO, N
   11: *     ..
   12: *     .. Array Arguments ..
   13:       COMPLEX*16         AP( * )
   14: *     ..
   15: *
   16: *  Purpose
   17: *  =======
   18: *
   19: *  ZPPTRI computes the inverse of a complex Hermitian positive definite
   20: *  matrix A using the Cholesky factorization A = U**H*U or A = L*L**H
   21: *  computed by ZPPTRF.
   22: *
   23: *  Arguments
   24: *  =========
   25: *
   26: *  UPLO    (input) CHARACTER*1
   27: *          = 'U':  Upper triangular factor is stored in AP;
   28: *          = 'L':  Lower triangular factor is stored in AP.
   29: *
   30: *  N       (input) INTEGER
   31: *          The order of the matrix A.  N >= 0.
   32: *
   33: *  AP      (input/output) COMPLEX*16 array, dimension (N*(N+1)/2)
   34: *          On entry, the triangular factor U or L from the Cholesky
   35: *          factorization A = U**H*U or A = L*L**H, packed columnwise as
   36: *          a linear array.  The j-th column of U or L is stored in the
   37: *          array AP as follows:
   38: *          if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
   39: *          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
   40: *
   41: *          On exit, the upper or lower triangle of the (Hermitian)
   42: *          inverse of A, overwriting the input factor U or L.
   43: *
   44: *  INFO    (output) INTEGER
   45: *          = 0:  successful exit
   46: *          < 0:  if INFO = -i, the i-th argument had an illegal value
   47: *          > 0:  if INFO = i, the (i,i) element of the factor U or L is
   48: *                zero, and the inverse could not be computed.
   49: *
   50: *  =====================================================================
   51: *
   52: *     .. Parameters ..
   53:       DOUBLE PRECISION   ONE
   54:       PARAMETER          ( ONE = 1.0D+0 )
   55: *     ..
   56: *     .. Local Scalars ..
   57:       LOGICAL            UPPER
   58:       INTEGER            J, JC, JJ, JJN
   59:       DOUBLE PRECISION   AJJ
   60: *     ..
   61: *     .. External Functions ..
   62:       LOGICAL            LSAME
   63:       COMPLEX*16         ZDOTC
   64:       EXTERNAL           LSAME, ZDOTC
   65: *     ..
   66: *     .. External Subroutines ..
   67:       EXTERNAL           XERBLA, ZDSCAL, ZHPR, ZTPMV, ZTPTRI
   68: *     ..
   69: *     .. Intrinsic Functions ..
   70:       INTRINSIC          DBLE
   71: *     ..
   72: *     .. Executable Statements ..
   73: *
   74: *     Test the input parameters.
   75: *
   76:       INFO = 0
   77:       UPPER = LSAME( UPLO, 'U' )
   78:       IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
   79:          INFO = -1
   80:       ELSE IF( N.LT.0 ) THEN
   81:          INFO = -2
   82:       END IF
   83:       IF( INFO.NE.0 ) THEN
   84:          CALL XERBLA( 'ZPPTRI', -INFO )
   85:          RETURN
   86:       END IF
   87: *
   88: *     Quick return if possible
   89: *
   90:       IF( N.EQ.0 )
   91:      $   RETURN
   92: *
   93: *     Invert the triangular Cholesky factor U or L.
   94: *
   95:       CALL ZTPTRI( UPLO, 'Non-unit', N, AP, INFO )
   96:       IF( INFO.GT.0 )
   97:      $   RETURN
   98:       IF( UPPER ) THEN
   99: *
  100: *        Compute the product inv(U) * inv(U)'.
  101: *
  102:          JJ = 0
  103:          DO 10 J = 1, N
  104:             JC = JJ + 1
  105:             JJ = JJ + J
  106:             IF( J.GT.1 )
  107:      $         CALL ZHPR( 'Upper', J-1, ONE, AP( JC ), 1, AP )
  108:             AJJ = AP( JJ )
  109:             CALL ZDSCAL( J, AJJ, AP( JC ), 1 )
  110:    10    CONTINUE
  111: *
  112:       ELSE
  113: *
  114: *        Compute the product inv(L)' * inv(L).
  115: *
  116:          JJ = 1
  117:          DO 20 J = 1, N
  118:             JJN = JJ + N - J + 1
  119:             AP( JJ ) = DBLE( ZDOTC( N-J+1, AP( JJ ), 1, AP( JJ ), 1 ) )
  120:             IF( J.LT.N )
  121:      $         CALL ZTPMV( 'Lower', 'Conjugate transpose', 'Non-unit',
  122:      $                     N-J, AP( JJN ), AP( JJ+1 ), 1 )
  123:             JJ = JJN
  124:    20    CONTINUE
  125:       END IF
  126: *
  127:       RETURN
  128: *
  129: *     End of ZPPTRI
  130: *
  131:       END