TESTING/LIN/dtpt02.f(3)    Library Functions Manual    TESTING/LIN/dtpt02.f(3)

NAME
       TESTING/LIN/dtpt02.f

SYNOPSIS
   Functions/Subroutines
       subroutine dtpt02 (uplo, trans, diag, n, nrhs, ap, x, ldx, b, ldb,
           work, resid)
           DTPT02

Function/Subroutine Documentation
   subroutine dtpt02 (character uplo, character trans, character diag, integer
       n, integer nrhs, double precision, dimension( * ) ap, double precision,
       dimension( ldx, * ) x, integer ldx, double precision, dimension( ldb, *
       ) b, integer ldb, double precision, dimension( * ) work, double
       precision resid)
       DTPT02

       Purpose:


            DTPT02 computes the residual for the computed solution to a
            triangular system of linear equations op(A)*X = B, when the
            triangular matrix A is stored in packed format. The test ratio is
            the maximum over
               norm(b - op(A)*x) / ( ||op(A)||_1 * norm(x) * EPS ),
            where op(A) = A or A**T, b is the column of B, x is the solution
            vector, and EPS is the machine epsilon.
            The norm used is the 1-norm.

       Parameters
           UPLO

                     UPLO is CHARACTER*1
                     Specifies whether the matrix A is upper or lower triangular.
                     = 'U':  Upper triangular
                     = 'L':  Lower triangular

           TRANS

                     TRANS is CHARACTER*1
                     Specifies the operation applied to A.
                     = '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
                     Specifies whether or not the matrix A is unit triangular.
                     = 'N':  Non-unit triangular
                     = 'U':  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 matrices X and 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((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;
                     if UPLO = 'L',
                        AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=n.

           X

                     X is DOUBLE PRECISION array, dimension (LDX,NRHS)
                     The computed solution vectors for the system of linear
                     equations.

           LDX

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

           B

                     B is DOUBLE PRECISION array, dimension (LDB,NRHS)
                     The right hand side vectors for the system of linear
                     equations.

           LDB

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

           WORK

                     WORK is DOUBLE PRECISION array, dimension (N)

           RESID

                     RESID is DOUBLE PRECISION
                     The maximum over the number of right hand sides of
                     norm(op(A)*X - B) / ( norm(op(A)) * norm(X) * EPS ).

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 140 of file dtpt02.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/LIN/dtpt02.f(3)