Renamed utils function

tupak/waveform_generator.py

@@ -94,7 +94,7 @@ class WaveformGenerator(object):
     @property
     def frequency_array(self):
         if self.__frequency_array_updated is False:
-            self.__frequency_array = utils.create_fequency_series(
+            self.__frequency_array = utils.create_frequency_series(
                                         self.sampling_frequency,
                                         self.time_duration)
             self.__frequency_array_updated = True