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Patches pour OS/2

    1:       SUBROUTINE DTPTRS( UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, 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          DIAG, TRANS, UPLO
   10:       INTEGER            INFO, LDB, N, NRHS
   11: *     ..
   12: *     .. Array Arguments ..
   13:       DOUBLE PRECISION   AP( * ), B( LDB, * )
   14: *     ..
   15: *
   16: *  Purpose
   17: *  =======
   18: *
   19: *  DTPTRS solves a triangular system of the form
   20: *
   21: *     A * X = B  or  A**T * X = B,
   22: *
   23: *  where A is a triangular matrix of order N stored in packed format,
   24: *  and B is an N-by-NRHS matrix.  A check is made to verify that A is
   25: *  nonsingular.
   26: *
   27: *  Arguments
   28: *  =========
   29: *
   30: *  UPLO    (input) CHARACTER*1
   31: *          = 'U':  A is upper triangular;
   32: *          = 'L':  A is lower triangular.
   33: *
   34: *  TRANS   (input) CHARACTER*1
   35: *          Specifies the form of the system of equations:
   36: *          = 'N':  A * X = B  (No transpose)
   37: *          = 'T':  A**T * X = B  (Transpose)
   38: *          = 'C':  A**H * X = B  (Conjugate transpose = Transpose)
   39: *
   40: *  DIAG    (input) CHARACTER*1
   41: *          = 'N':  A is non-unit triangular;
   42: *          = 'U':  A is unit triangular.
   43: *
   44: *  N       (input) INTEGER
   45: *          The order of the matrix A.  N >= 0.
   46: *
   47: *  NRHS    (input) INTEGER
   48: *          The number of right hand sides, i.e., the number of columns
   49: *          of the matrix B.  NRHS >= 0.
   50: *
   51: *  AP      (input) DOUBLE PRECISION array, dimension (N*(N+1)/2)
   52: *          The upper or lower triangular matrix A, packed columnwise in
   53: *          a linear array.  The j-th column of A is stored in the array
   54: *          AP as follows:
   55: *          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
   56: *          if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.
   57: *
   58: *  B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
   59: *          On entry, the right hand side matrix B.
   60: *          On exit, if INFO = 0, the solution matrix X.
   61: *
   62: *  LDB     (input) INTEGER
   63: *          The leading dimension of the array B.  LDB >= max(1,N).
   64: *
   65: *  INFO    (output) INTEGER
   66: *          = 0:  successful exit
   67: *          < 0:  if INFO = -i, the i-th argument had an illegal value
   68: *          > 0:  if INFO = i, the i-th diagonal element of A is zero,
   69: *                indicating that the matrix is singular and the
   70: *                solutions X have not been computed.
   71: *
   72: *  =====================================================================
   73: *
   74: *     .. Parameters ..
   75:       DOUBLE PRECISION   ZERO
   76:       PARAMETER          ( ZERO = 0.0D+0 )
   77: *     ..
   78: *     .. Local Scalars ..
   79:       LOGICAL            NOUNIT, UPPER
   80:       INTEGER            J, JC
   81: *     ..
   82: *     .. External Functions ..
   83:       LOGICAL            LSAME
   84:       EXTERNAL           LSAME
   85: *     ..
   86: *     .. External Subroutines ..
   87:       EXTERNAL           DTPSV, XERBLA
   88: *     ..
   89: *     .. Intrinsic Functions ..
   90:       INTRINSIC          MAX
   91: *     ..
   92: *     .. Executable Statements ..
   93: *
   94: *     Test the input parameters.
   95: *
   96:       INFO = 0
   97:       UPPER = LSAME( UPLO, 'U' )
   98:       NOUNIT = LSAME( DIAG, 'N' )
   99:       IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
  100:          INFO = -1
  101:       ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.
  102:      $         LSAME( TRANS, 'T' ) .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
  103:          INFO = -2
  104:       ELSE IF( .NOT.NOUNIT .AND. .NOT.LSAME( DIAG, 'U' ) ) THEN
  105:          INFO = -3
  106:       ELSE IF( N.LT.0 ) THEN
  107:          INFO = -4
  108:       ELSE IF( NRHS.LT.0 ) THEN
  109:          INFO = -5
  110:       ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
  111:          INFO = -8
  112:       END IF
  113:       IF( INFO.NE.0 ) THEN
  114:          CALL XERBLA( 'DTPTRS', -INFO )
  115:          RETURN
  116:       END IF
  117: *
  118: *     Quick return if possible
  119: *
  120:       IF( N.EQ.0 )
  121:      $   RETURN
  122: *
  123: *     Check for singularity.
  124: *
  125:       IF( NOUNIT ) THEN
  126:          IF( UPPER ) THEN
  127:             JC = 1
  128:             DO 10 INFO = 1, N
  129:                IF( AP( JC+INFO-1 ).EQ.ZERO )
  130:      $            RETURN
  131:                JC = JC + INFO
  132:    10       CONTINUE
  133:          ELSE
  134:             JC = 1
  135:             DO 20 INFO = 1, N
  136:                IF( AP( JC ).EQ.ZERO )
  137:      $            RETURN
  138:                JC = JC + N - INFO + 1
  139:    20       CONTINUE
  140:          END IF
  141:       END IF
  142:       INFO = 0
  143: *
  144: *     Solve A * x = b  or  A' * x = b.
  145: *
  146:       DO 30 J = 1, NRHS
  147:          CALL DTPSV( UPLO, TRANS, DIAG, N, AP, B( 1, J ), 1 )
  148:    30 CONTINUE
  149: *
  150:       RETURN
  151: *
  152: *     End of DTPTRS
  153: *
  154:       END