From ec3887a4dcee3984c009e59d67e4ea54e38f31f3 Mon Sep 17 00:00:00 2001
From: xadupre <xadupre@microsoft.com>
Date: Tue, 11 Jun 2024 10:05:58 +0000
Subject: [PATCH] comment

---
 operators/cuda/rotary.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/operators/cuda/rotary.h b/operators/cuda/rotary.h
index a365c2470..b5e27b877 100644
--- a/operators/cuda/rotary.h
+++ b/operators/cuda/rotary.h
@@ -8,6 +8,16 @@
 
 namespace contrib {
 
+/**
+*  Y = Rotary(X) is equivalent to if side == LEFT:
+*
+*   N = X.shape[-1]
+*   Y = X.copy()
+*   Y[...,:N/2] = X[...,N/2:]
+*   Y[...,N/2:] = -X[...,:N/2]
+*
+*   And the opposite if side == RIGHT.
+*/
 template <typename T>
 struct Rotary {
   template <typename TDict>