dtbt03.f3

!>
!> DTBT03 computes the residual for the solution to a scaled triangular
!> system of equations  A*x = s*b  or  A'*x = s*b  when A is a
!> triangular band matrix. Here A' is the 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 or A' and EPS is the machine epsilon.
!> 

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'*x = b  (Transpose)
!>          = 'C':  A'*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 DOUBLE PRECISION 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 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 - s*b) / ( norm(op(A)) * norm(x) * EPS ).
!> 

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