[SciPy-user] Inexact Newton methods in scipy
Nils Wagner
nwagner at mecha.uni-stuttgart.de
Fri Nov 12 06:35:30 CST 2004
Hi all,
A standard method to solve nonlinear equations
f(x) = 0
is Newton's method. Given a suitable initial guess one iterates
f'(x_k) \Delta x_k = -f(x_k)
x_{k+1} = x_k + \Delta x_k
If the Jacobian is not available in a direct manner, we can apply f'(x_k) to a vector \Delta x_k by a finite difference formula (see my previous mail fdf package)
BTW, most publications deal with real Jacobians. How can I extend finite
difference formulas to complex Jacobians ?
help (linalg.gmres) yields
A -- An array or an object with a matvec(x) method
to represent A * x
A small example illustrating an object with a matvec(x) method would be appreciated.
Nils
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