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Earth and Space Sciences · 术语表

什么是 Damped least squares, trade-off curve?

又称: damped least squares · trade-off curve

Definition 1.12 University Earth and Space Sciences — Year 3 · 第 1 章 — Seismology and Earth Imaging

For a damping parameter ε>0\varepsilon > 0, the damped least squares estimate is the model that minimises

Φε(m)=χ2(m)+ε2∥m∥2,mε=(N+ε2I)−1GTCd−1d.\Phi_\varepsilon(\mathbf m) = \chi^2(\mathbf m) + \varepsilon^2\|\mathbf m\|^2 , \qquad \mathbf m_\varepsilon = \left(\mathsf N + \varepsilon^2\mathsf I\right)^{-1} \mathsf G^{\mathsf T}\mathsf C_d^{-1}\mathbf d .

The trade-off curve is the curve traced, as ε\varepsilon varies, by the pair (size of the model ∥mε∥\|\mathbf m_\varepsilon\|, misfit χ2(mε)\chi^2(\mathbf m_\varepsilon)): small damping fits the data closely with a large, rough model, large damping gives a small model and a poor fit.

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