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arXiv 0810.4185math.NAcs.NA
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关于求解非线性反问题的某些牛顿型方法的偏差原则

On the discrepancy principle for some Newton type methods for solving nonlinear inverse problems

The University of Texas at Austin(德克萨斯大学奥斯汀分校);University of Applied Sciences Zittau/Görlitz(齐陶/格罗利茨应用科学大学)

Qinian Jin, Ulrich Tautenhahn

AI总结:

针对非线性不适定反问题,提出用牛顿型方法结合偏差原则进行迭代终止,在噪声数据下证明了收敛性和最优收敛速率。

摘要:

我们考虑用牛顿型方法 $$ x_{k+1}^δ=x_0-g_{α_k} (F'(x_k^δ)^*F'(x_k^δ)) F'(x_k^δ)^* (F(x_k^δ)-y^δ-F'(x_k^δ)(x_k^δ-x_0)) $$ 计算非线性不适定反问题 $F(x)=y$ 的精确解 $x^†$ 的稳定逼近,其中 $F:X\to Y$ 是两个 Hilbert 空间 $X$ 和 $Y$ 之间的非线性算子,且仅有的可用数据是 $y$ 的带噪数据 $y^δ$,满足 $\|y^δ-y\|\le δ$,其中 $δ>0$ 是给定的噪声水平。我们通过偏差原则终止迭代,其中停止指标 $k_δ$ 是使得 $$ \|F(x_{k_δ}^δ)-y^δ\|\le τδ<\|F(x_k^δ)-y^δ\|, \qquad 0\le k<k_δ$$ 成立的第一个整数,$τ>1$ 是给定常数。在 $\{α_k\}$、$\{g_α\}$ 和 $F$ 的某些条件下,我们证明当 $δ o 0$ 时 $x_{k_δ}^δ$ 收敛到 $x^†$,并建立各种阶最优收敛速率结果。值得注意的是,如果 $x_0-x^†$ 足够光滑,我们甚至可以在仅对 $F$ 的 Fréchet 导数 $F'$ 施加 Lipschitz 条件的情况下证明阶最优性。

英文摘要:

We consider the computation of stable approximations to the exact solution $x^†$ of nonlinear ill-posed inverse problems $F(x)=y$ with nonlinear operators $F:X\to Y$ between two Hilbert spaces $X$ and $Y$ by the Newton type methods $$ x_{k+1}^δ=x_0-g_{α_k} (F'(x_k^δ)^*F'(x_k^δ)) F'(x_k^δ)^* (F(x_k^δ)-y^δ-F'(x_k^δ)(x_k^δ-x_0)) $$ in the case that only available data is a noise $y^δ$ of $y$ satisfying $\|y^δ-y\|\le δ$ with a given small noise level $δ>0$. We terminate the iteration by the discrepancy principle in which the stopping index $k_δ$ is determined as the first integer such that $$ \|F(x_{k_δ}^δ)-y^δ\|\le τδ<\|F(x_k^δ)-y^δ\|, \qquad 0\le k<k_δ$$ with a given number $τ>1$. Under certain conditions on $\{α_k\}$, $\{g_α\}$ and $F$, we prove that $x_{k_δ}^δ$ converges to $x^†$ as $δ\to 0$ and establish various order optimal convergence rate results. It is remarkable that we even can show the order optimality under merely the Lipschitz condition on the Fréchet derivative $F'$ of $F$ if $x_0-x^†$ is smooth enough.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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