TESTING/LIN/stbt06.f(3)    Library Functions Manual    TESTING/LIN/stbt06.f(3)

NAME
       TESTING/LIN/stbt06.f

SYNOPSIS
   Functions/Subroutines
       subroutine stbt06 (rcond, rcondc, uplo, diag, n, kd, ab, ldab, work,
           rat)
           STBT06

Function/Subroutine Documentation
   subroutine stbt06 (real rcond, real rcondc, character uplo, character diag,
       integer n, integer kd, real, dimension( ldab, * ) ab, integer ldab,
       real, dimension( * ) work, real rat)
       STBT06

       Purpose:


            STBT06 computes a test ratio comparing RCOND (the reciprocal
            condition number of a triangular matrix A) and RCONDC, the estimate
            computed by STBCON.  Information about the triangular matrix A is
            used if one estimate is zero and the other is non-zero to decide if
            underflow in the estimate is justified.

       Parameters
           RCOND

                     RCOND is REAL
                     The estimate of the reciprocal condition number obtained by
                     forming the explicit inverse of the matrix A and computing
                     RCOND = 1/( norm(A) * norm(inv(A)) ).

           RCONDC

                     RCONDC is REAL
                     The estimate of the reciprocal condition number computed by
                     STBCON.

           UPLO

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

           DIAG

                     DIAG is CHARACTER
                     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.

           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.

           WORK

                     WORK is REAL array, dimension (N)

           RAT

                     RAT is REAL
                     The test ratio.  If both RCOND and RCONDC are nonzero,
                        RAT = MAX( RCOND, RCONDC )/MIN( RCOND, RCONDC ) - 1.
                     If RAT = 0, the two estimates are exactly the same.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 123 of file stbt06.f.

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

LAPACK                          Version 3.12.0         TESTING/LIN/stbt06.f(3)