matlab 矢量化编程（三） —— 软阈值函数

$$\hat{d_{j,k}}=\left\{ \begin{array}{l} d_{j,k}-\lambda,\quad d_{j,k}\geq \lambda \\ 0,\quad \text{otherwise}\\ d_{j,k}+\lambda,\quad d_{j,k}\leq -\lambda \end{array} \right.$$

function y = soft(x, T)
y = (x - abs(T) > 0) .* x