Update frontend.py

frontend.py

@@ -6,7 +6,9 @@ history = []
 
 def calculate(expression):
     try:
-        response = requests.post("/calculate", json={"expr": expression})
+        # Use the current page's URL to construct the API endpoint
+        api_url = gr.get_url() + "/calculate"
+        response = requests.post(api_url, json={"expr": expression})
         if response.status_code == 200:
             result = response.json()["result"]
             result_str = f"{result:.8f}".rstrip('0').rstrip('.')