diff --git a/jointContribution/PIRBN/rbn_net.py b/jointContribution/PIRBN/rbn_net.py
index d03e27f88..d148c5187 100644
--- a/jointContribution/PIRBN/rbn_net.py
+++ b/jointContribution/PIRBN/rbn_net.py
@@ -69,7 +69,6 @@ def __init__(self, n_neu, c, input_shape_last):
         )
 
     def forward(self, inputs):  # Defines the computation from inputs to outputs
-        s = self.b * self.b
         temp_x = paddle.matmul(inputs, paddle.ones((1, self.n_neu)))
         x0 = (
             paddle.reshape(
@@ -80,5 +79,10 @@ def forward(self, inputs):  # Defines the computation from inputs to outputs
             / (self.n_neu - 1)
             + self.c[0]
         )
-        x_new = (temp_x - x0) * (temp_x - x0)
-        return paddle.exp(-x_new * s)
+        x_new = temp_x - x0
+        return self.rbf_activate(x_new)
+
+    # activation function
+    def rbf_activate(self, input):
+        s = self.b * self.b
+        return paddle.exp(-(input * input) * s)