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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine ztbt02 | ( | character | UPLO, |
character | TRANS, | ||
character | DIAG, | ||
integer | N, | ||
integer | KD, | ||
integer | NRHS, | ||
complex*16, dimension( ldab, * ) | AB, | ||
integer | LDAB, | ||
complex*16, dimension( ldx, * ) | X, | ||
integer | LDX, | ||
complex*16, dimension( ldb, * ) | B, | ||
integer | LDB, | ||
complex*16, dimension( * ) | WORK, | ||
double precision, dimension( * ) | RWORK, | ||
double precision | RESID | ||
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ZTBT02
ZTBT02 computes the residual for the computed solution to a triangular system of linear equations A*x = b, A**T *x = b, or A**H *x = b when A is a triangular band matrix. Here A**T denotes the transpose of A, A**H denotes the conjugate transpose of A, and x and b are N by NRHS matrices. The test ratio is the maximum over the number of right hand sides of norm(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 = b (No transpose) = 'T': A**T *x = b (Transpose) = 'C': A**H *x = 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 (LDA,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 >= max(1,KD+1). |
[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] | RWORK | RWORK is DOUBLE PRECISION array, dimension (N) |
[out] | RESID | RESID is DOUBLE PRECISION The maximum over the number of right hand sides of norm(op(A)*x - b) / ( norm(op(A)) * norm(x) * EPS ). |
Definition at line 163 of file ztbt02.f.