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

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