CGTT02
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
November 2006
November 2006
Purpose
CGTT02 computes the residual for the solution to a tridiagonal
system of equations:
RESID = norm(B - op(A)*X) / (norm(A) * norm(X) * EPS),
where EPS is the machine epsilon.
system of equations:
RESID = norm(B - op(A)*X) / (norm(A) * norm(X) * EPS),
where EPS is the machine epsilon.
Arguments
| TRANS |
(input) CHARACTER
Specifies the form of the residual.
= 'N': B - A * X (No transpose) = 'T': B - A**T * X (Transpose) = 'C': B - A**H * X (Conjugate transpose) |
| N |
(input) INTEGTER
The order of the matrix A. N >= 0.
|
| NRHS |
(input) INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices B and X. NRHS >= 0. |
| DL |
(input) COMPLEX array, dimension (N-1)
The (n-1) sub-diagonal elements of A.
|
| D |
(input) COMPLEX array, dimension (N)
The diagonal elements of A.
|
| DU |
(input) COMPLEX array, dimension (N-1)
The (n-1) super-diagonal elements of A.
|
| X |
(input) COMPLEX array, dimension (LDX,NRHS)
The computed solution vectors X.
|
| LDX |
(input) INTEGER
The leading dimension of the array X. LDX >= max(1,N).
|
| B |
(input/output) COMPLEX array, dimension (LDB,NRHS)
On entry, the right hand side vectors for the system of
linear equations. On exit, B is overwritten with the difference B - op(A)*X. |
| LDB |
(input) INTEGER
The leading dimension of the array B. LDB >= max(1,N).
|
| RWORK |
(workspace) REAL array, dimension (N)
|
| RESID |
(output) REAL
norm(B - op(A)*X) / (norm(A) * norm(X) * EPS)
|