diff --git a/src/shape_functions.jl b/src/shape_functions.jl
index adc0e66..1b858d7 100644
--- a/src/shape_functions.jl
+++ b/src/shape_functions.jl
@@ -1,3 +1,14 @@
 function test(a)
      return a*2
 end
+
+
+function C2D4(xx)
+     chi = xx[1]
+     eta = xx[2]
+     return = [(1 - chi) * (1 - eta),
+               chi * (1 - eta),
+               chi * eta,
+               (1 - chi) * eta]
+end
+