NAME

       dtptrs.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dtptrs (UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, INFO)
           DTPTRS

Function/Subroutine Documentation

   subroutine dtptrs (characterUPLO, characterTRANS, characterDIAG, integerN, integerNRHS, double
       precision, dimension( * )AP, double precision, dimension( ldb, * )B, integerLDB,
       integerINFO)
       DTPTRS

       Purpose:

            DTPTRS solves a triangular system of the form

               A * X = B  or  A**T * X = B,

            where A is a triangular matrix of order N stored in packed format,
            and B is an N-by-NRHS matrix.  A check is made to verify that A is
            nonsingular.

       Parameters:
           UPLO

                     UPLO is CHARACTER*1
                     = 'U':  A is upper triangular;
                     = 'L':  A is lower triangular.

           TRANS

                     TRANS is CHARACTER*1
                     Specifies the form of the system of equations:
                     = 'N':  A * X = B  (No transpose)
                     = 'T':  A**T * X = B  (Transpose)
                     = 'C':  A**H * X = B  (Conjugate transpose = Transpose)

           DIAG

                     DIAG is CHARACTER*1
                     = 'N':  A is non-unit triangular;
                     = 'U':  A is unit triangular.

           N

                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           NRHS

                     NRHS is INTEGER
                     The number of right hand sides, i.e., the number of columns
                     of the matrix B.  NRHS >= 0.

           AP

                     AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
                     The upper or lower triangular matrix A, packed columnwise in
                     a linear array.  The j-th column of A is stored in the array
                     AP as follows:
                     if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
                     if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.

           B

                     B is DOUBLE PRECISION array, dimension (LDB,NRHS)
                     On entry, the right hand side matrix B.
                     On exit, if INFO = 0, the solution matrix X.

           LDB

                     LDB is INTEGER
                     The leading dimension of the array B.  LDB >= max(1,N).

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0:  if INFO = -i, the i-th argument had an illegal value
                     > 0:  if INFO = i, the i-th diagonal element of A is zero,
                           indicating that the matrix is singular and the
                           solutions X have not been computed.

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           November 2011

       Definition at line 131 of file dtptrs.f.

Author

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