TESTING/LIN/stbt02.f(3)    Library Functions Manual    TESTING/LIN/stbt02.f(3)

NAME
       TESTING/LIN/stbt02.f

SYNOPSIS
   Functions/Subroutines
       subroutine stbt02 (uplo, trans, diag, n, kd, nrhs, ab, ldab, x, ldx, b,
           ldb, work, resid)
           STBT02

Function/Subroutine Documentation
   subroutine stbt02 (character uplo, character trans, character diag, integer
       n, integer kd, integer nrhs, real, dimension( ldab, * ) ab, integer
       ldab, real, dimension( ldx, * ) x, integer ldx, real, dimension( ldb, *
       ) b, integer ldb, real, dimension( * ) work, real resid)
       STBT02

       Purpose:


            STBT02 computes the residual for the computed solution to a
            triangular system of linear equations op(A)*X = B, when A is a
            triangular band matrix. 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.

           KD

                     KD is INTEGER
                     The number of superdiagonals or subdiagonals of the
                     triangular band matrix A.  KD >= 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.

           AB

                     AB is REAL array, dimension (LDAB,N)
                     The upper or lower triangular band matrix A, stored in the
                     first kd+1 rows of the array. The j-th column of A is stored
                     in the j-th column of the array AB as follows:
                     if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;
                     if UPLO = 'L', AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd).

           LDAB

                     LDAB is INTEGER
                     The leading dimension of the array AB.  LDAB >= KD+1.

           X

                     X is REAL 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 REAL 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 REAL array, dimension (N)

           RESID

                     RESID is REAL
                     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 152 of file stbt02.f.

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

LAPACK                          Version 3.12.0         TESTING/LIN/stbt02.f(3)