diff --git a/doc/AsciiQuickReference.txt b/doc/AsciiQuickReference.txt
index 398482b13..c4d021624 100644
--- a/doc/AsciiQuickReference.txt
+++ b/doc/AsciiQuickReference.txt
@@ -91,6 +91,7 @@ R.adjoint()                        // R'
 R.transpose()                      // R.' or conj(R')
 R.diagonal()                       // diag(R)
 x.asDiagonal()                     // diag(x)
+R.transpose().colwise().reverse(); // rot90(R)
 
 // All the same as Matlab, but matlab doesn't have *= style operators.
 // Matrix-vector.  Matrix-matrix.   Matrix-scalar.