diff --git a/Zframework/mathExtend.lua b/Zframework/mathExtend.lua
index 5f3db7c3..9eb5786b 100644
--- a/Zframework/mathExtend.lua
+++ b/Zframework/mathExtend.lua
@@ -20,6 +20,10 @@ function MATH.coin(a,b)
     end
 end
 
+function MATH.lerp(s,e,t)
+    return s+(e-s)*t
+end
+
 function MATH.interval(v,low,high)
     if v<=low then
         return low
@@ -34,4 +38,4 @@ function MATH.expApproach(a,b,k)
     return b+(a-b)*2.718281828459045^-k
 end
 
-return MATH
\ No newline at end of file
+return MATH