Learning the Mapping x ↦ $\sum\limits_{i = 1}^d {x_i^2}$: the Cost of Finding the Needle in a Haystack

Jiefu Zhang, Leonardo Zepeda-Núñez, Yuan Yao, Lin Lin

Communications on Applied Mathematics and Computation . 2021, (2): 313 -335 . DOI: 10.1007/s42967-020-00078-2