This paper provides a one-line proof of Frequent Directions (FD) for sketching streams of matrices. The simpler proof arises from sketching the covariance of the stream of matrices rather than the stream itself.

翻译：本文以一线证据来证明对矩阵的草图流的 " 常态指示 " (FD),更简单的证明来自对矩阵流的共变量而不是流本身的共变量的草图。