# 稀疏编码自编码表达

### From Ufldl

(→Sparse coding) |
(→Sparse coding[稀疏编码]) |
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Unfortunately, the objective function is non-convex, and hence impossible to optimize well using gradient-based methods. However, given <math>A</math>, the problem of finding <math>s</math> that minimizes <math>J(A, s)</math> is convex. Similarly, given <math>s</math>, the problem of finding <math>A</math> that minimizes <math>J(A, s)</math> is also convex. This suggests that we might try alternately optimizing for <math>A</math> for a fixed <math>s</math>, and then optimizing for <math>s</math> given a fixed <math>A</math>. It turns out that this works quite well in practice. | Unfortunately, the objective function is non-convex, and hence impossible to optimize well using gradient-based methods. However, given <math>A</math>, the problem of finding <math>s</math> that minimizes <math>J(A, s)</math> is convex. Similarly, given <math>s</math>, the problem of finding <math>A</math> that minimizes <math>J(A, s)</math> is also convex. This suggests that we might try alternately optimizing for <math>A</math> for a fixed <math>s</math>, and then optimizing for <math>s</math> given a fixed <math>A</math>. It turns out that this works quite well in practice. | ||

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[初译] | [初译] |