diff --git a/Homeworks/2_ImageWarping/documents/0_IDW.md b/Homeworks/2_ImageWarping/documents/0_IDW.md
index 7eb727ca..0d42e7b7 100644
--- a/Homeworks/2_ImageWarping/documents/0_IDW.md
+++ b/Homeworks/2_ImageWarping/documents/0_IDW.md
@@ -11,7 +11,7 @@
 局部插值函数 $\mathbf{f} _ i(\mathbf{p}):\mathbb{R}^2\to\mathbb{R}^2$ 满足 $f _ i(\mathbf{p} _ i)=\mathbf{q} _ i$，具体为
 
 $$
-\mathbf{f} _ i(\mathbf{p})=\mathbf{q} _ i+\mathbf{D} _ i(\mathbf{p}-\mathbf{q} _ i)
+\mathbf{f} _ i(\mathbf{p})=\mathbf{q} _ i+\mathbf{D} _ i(\mathbf{p}-\mathbf{p} _ i)
 $$
 其中 $\mathbf{D} _ i:\mathbb{R}^2\to\mathbb{R}^2$，满足 $\mathbf{D} _ i(\mathbf{0})=\mathbf{0}$