dtpsv.f(3)

NAME
dtpsv.f -

SYNOPSIS

  Functions/Subroutines
subroutine dtpsv (UPLO, TRANS, DIAG, N, AP, X, INCX)
DTPSV

Function/Subroutine Documentation

  subroutine dtpsv (characterUPLO, characterTRANS, characterDIAG, integerN, double precision, dimension(*)AP, double precision, dimension(*)X, integerINCX)

DTPSV Purpose:

     DTPSV  solves one of the systems of equations
        A*x = b,   or   A**T*x = b,
     where b and x are n element vectors and A is an n by n unit, or
     non-unit, upper or lower triangular matrix, supplied in packed form.
     No test for singularity or near-singularity is included in this
     routine. Such tests must be performed before calling this routine.

Parameters:
    UPLO

              UPLO is CHARACTER*1
               On entry, UPLO specifies whether the matrix is an upper or
               lower triangular matrix as follows:
                  UPLO = 'U' or 'u'   A is an upper triangular matrix.
                  UPLO = 'L' or 'l'   A is a lower triangular matrix.

    TRANS

              TRANS is CHARACTER*1
               On entry, TRANS specifies the equations to be solved as
               follows:
                  TRANS = 'N' or 'n'   A*x = b.
                  TRANS = 'T' or 't'   A**T*x = b.
                  TRANS = 'C' or 'c'   A**T*x = b.

    DIAG

              DIAG is CHARACTER*1
               On entry, DIAG specifies whether or not A is unit
               triangular as follows:
                  DIAG = 'U' or 'u'   A is assumed to be unit triangular.
                  DIAG = 'N' or 'n'   A is not assumed to be unit
                                      triangular.

    N

              N is INTEGER
               On entry, N specifies the order of the matrix A.
               N must be at least zero.

    AP

              AP is DOUBLE PRECISION array of DIMENSION at least
               ( ( n*( n + 1 ) )/2 ).
               Before entry with  UPLO = 'U' or 'u', the array AP must
               contain the upper triangular matrix packed sequentially,
               column by column, so that AP( 1 ) contains a( 1, 1 ),
               AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 )
               respectively, and so on.
               Before entry with UPLO = 'L' or 'l', the array AP must
               contain the lower triangular matrix packed sequentially,
               column by column, so that AP( 1 ) contains a( 1, 1 ),
               AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 )
               respectively, and so on.
               Note that when  DIAG = 'U' or 'u', the diagonal elements of
               A are not referenced, but are assumed to be unity.

    X

              X is DOUBLE PRECISION array of dimension at least
               ( 1 + ( n - 1 )*abs( INCX ) ).
               Before entry, the incremented array X must contain the n
               element right-hand side vector b. On exit, X is overwritten
               with the solution vector x.

    INCX

              INCX is INTEGER
               On entry, INCX specifies the increment for the elements of
               X. INCX must not be zero.

Author:
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Date:
    November 2011

Further Details:

      Level 2 Blas routine.
      -- Written on 22-October-1986.
         Jack Dongarra, Argonne National Lab.
         Jeremy Du Croz, Nag Central Office.
         Sven Hammarling, Nag Central Office.
         Richard Hanson, Sandia National Labs.

Definition at line 145 of file dtpsv.f.

Author

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