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qmr
quasi minimal resiqual method with preconditioning
Calling Sequence
[x,flag,err,iter,res] = qmr(A,b,x0,M1,M1p,M2,M2p,maxi,tol)
Arguments
- A
matrix of size n-by-n or function returning
A*x
- b
right hand side vector
- x0
initial guess vector (default: zeros(n,1))
- M1
left preconditioner: matrix or function returning
M1*x
(In the first case, default: eye(n,n))- M1p
must only be provided when
M1
is a function. In this caseM1p
is the function which returnsM1'*x
- M2
right preconditioner: matrix or function returning
M2*x
(In the first case, default: eye(n,n))- M2p
must only be provided when
M2
is a function. In this caseM2p
is the function which returnsM2'*x
- maxi
maximum number of iterations (default: n)
- tol
error tolerance (default: 1000*%eps)
- x
solution vector
- flag
- 0 =
gmres
converged to the desired tolerance withinmaxi
iterations- 1 =
no convergence given
maxi
- res
residual vector
- err
final residual norm
- iter
number of iterations performed
Description
Solves the linear system Ax=b
using the Quasi Minimal Residual Method with preconditioning.
See Also
- gmres — Generalized Minimum RESidual method
Authors
SAGE Group, IRISA 2005
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