 |
LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
|
|
LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
|
| 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
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. | [in] | UPLO | UPLO is CHARACTER*1
Specifies whether the matrix A is upper or lower triangular.
= 'U': Upper triangular
= 'L': Lower triangular |
| [in] | 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) |
| [in] | DIAG | DIAG is CHARACTER*1
Specifies whether or not the matrix A is unit triangular.
= 'N': Non-unit triangular
= 'U': Unit triangular |
| [in] | N | N is INTEGER
The order of the matrix A. N >= 0. |
| [in] | KD | KD is INTEGER
The number of superdiagonals or subdiagonals of the
triangular band matrix A. KD >= 0. |
| [in] | NRHS | NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices X and B. NRHS >= 0. |
| [in] | 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). |
| [in] | LDAB | LDAB is INTEGER
The leading dimension of the array AB. LDAB >= KD+1. |
| [in] | SCALE | SCALE is DOUBLE PRECISION
The scaling factor s used in solving the triangular system. |
| [in] | CNORM | CNORM is DOUBLE PRECISION array, dimension (N)
The 1-norms of the columns of A, not counting the diagonal. |
| [in] | 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. |
| [in] | X | X is COMPLEX*16 array, dimension (LDX,NRHS)
The computed solution vectors for the system of linear
equations. |
| [in] | LDX | LDX is INTEGER
The leading dimension of the array X. LDX >= max(1,N). |
| [in] | B | B is COMPLEX*16 array, dimension (LDB,NRHS)
The right hand side vectors for the system of linear
equations. |
| [in] | LDB | LDB is INTEGER
The leading dimension of the array B. LDB >= max(1,N). |
| [out] | WORK | WORK is COMPLEX*16 array, dimension (N) |
| [out] | 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 ). |
Definition at line 179 of file ztbt03.f.
1.8.10