Update 2021JUL21.md

2021JUL21.md

@@ -153,7 +153,8 @@ XLtrain[:, rand(1:n_samples, Int(round(n_samples / 10)))] .= randn(d, Int(round(
  - d = 10
 
 ![](/figs/2021AUG01/d10.svg)
-### U
+### Estimation of the transformation (rotation) matrix U
+Here the yaxis are Frobenius norm $`||\hat{\mathbf{U}}\text{XHmean} - \mathbf{Utrue}\text{XHmean}||^{2}_{F}`$
  - d = 3
 
 ![](/figs/2021AUG01/d3_U.svg)