newer scipy does not seem to have attribute pi

Author: fangohr

book/16-scipy.ipynb

@@ -1043,7 +1043,7 @@
     "import scipy.fft\n",
     "import numpy as np\n",
     "import matplotlib.pyplot as plt\n",
-    "pi = scipy.pi\n",
+    "pi = np.pi\n",
     "\n",
     "signal_length = 0.5     # [seconds]\n",
     "sample_rate = 500       # sampling rate [Hz]\n",
@@ -1335,4 +1335,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 1
-}
+}