TESTING/LIN/ztbt03.f(3)

NAME
TESTING/LIN/ztbt03.f

SYNOPSIS

  Functions/Subroutines
subroutine ztbt03 (uplo, trans, diag, n, kd, nrhs, ab, ldab, scale, cnorm, tscal, x, ldx, b, ldb, work, resid)
ZTBT03

Function/Subroutine Documentation

  subroutine ztbt03 (character uplo, character trans, character diag, integer n, integer kd, integer nrhs, complex*16, dimension( ldab, * ) ab, integer ldab, double precision scale, double precision, dimension( * ) cnorm, double precision tscal, complex*16, dimension( ldx, * ) x, integer ldx, complex*16, dimension( ldb, * ) b, integer ldb, complex*16, dimension( * ) work, double precision resid)

ZTBT03

Purpose:

    !>
    !> ZTBT03 computes the residual for the solution to a scaled triangular
    !> system of equations  A*x = s*b,  A**T *x = s*b,  or  A**H *x = s*b
    !> when A is a triangular band matrix.  Here A**T  denotes the transpose
    !> of A, A**H denotes the conjugate transpose of A, s is a scalar, and
    !> x and b are N by NRHS matrices.  The test ratio is the maximum over
    !> the number of right hand sides of
    !>    norm(s*b - op(A)*x) / ( norm(op(A)) * norm(x) * EPS ),
    !> where op(A) denotes A, A**T, or A**H, and EPS is the machine epsilon.
    !>

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 = s*b     (No transpose)
    !>          = 'T':  A**T *x = s*b  (Transpose)
    !>          = 'C':  A**H *x = s*b  (Conjugate 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 COMPLEX*16 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.
    !>

    SCALE

    !>          SCALE is DOUBLE PRECISION
    !>          The scaling factor s used in solving the triangular system.
    !>

    CNORM

    !>          CNORM is DOUBLE PRECISION array, dimension (N)
    !>          The 1-norms of the columns of A, not counting the diagonal.
    !>

    TSCAL

    !>          TSCAL is DOUBLE PRECISION
    !>          The scaling factor used in computing the 1-norms in CNORM.
    !>          CNORM actually contains the column norms of TSCAL*A.
    !>

    X

    !>          X is COMPLEX*16 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 COMPLEX*16 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 COMPLEX*16 array, dimension (N)
    !>

    RESID

    !>          RESID is DOUBLE PRECISION
    !>          The maximum over the number of right hand sides of
    !>          norm(op(A)*x - s*b) / ( norm(op(A)) * norm(x) * EPS ).
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 174 of file ztbt03.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.