[signals] First pass at signal module -- it doesn't import???

signal/waves.py

@@ -0,0 +1,49 @@
+# waves.py
+# Eryn Wells <eryn@erynwells.me>
+'''
+Several functions for creating audio waves.
+'''
+
+import numpy as np
+
+__default_num_harmonics = 10
+
+def sine(domain, freq=1.0):
+    '''Render a sine wave in the given domain with the specified frequency.'''
+    return np.sin(2.0 * np.pi * freq * domain)
+
+def saw(domain, freq=1.0, num_harmonics=__default_num_harmonics):
+    '''
+    Render a saw wave in the given domain at the specified frequency.
+
+    This function produces a saw wave by computing the first `harmonics` terms of the
+    infinite series defining its shape.
+    '''
+    harmonics = np.asarray([1.0 / h * sine(domain, freq=freq * h) for h in range(1, num_harmonics)])
+    wave = np.sum(harmonics, axis=0)
+    return wave
+
+def square(domain, freq=1, num_harmonics=__default_num_harmonics):
+    '''
+    Render a square wave in the given domain at the specified frequency.
+
+    This function produces a saw wave by computing the first `harmonics` terms of the
+    infinite series defining its shape.
+    '''
+    harmonics = np.asarray([1.0 / h * sine(domain, freq=freq * h) for h in range(1, num_harmonics, 2)])
+    wave = np.sum(harmonics, axis=0)
+    return wave
+
+def triangle(domain, freq=1, num_harmonics=__default_num_harmonics):
+    '''
+    Render a triangle wave in the given domain at the specified frequency.
+
+    This function produces a saw wave by computing the first `num_harmonics` terms of the
+    infinite series defining its shape.
+    '''
+    def label(i):
+        return 2.0 * i + 1.0
+    harmonics = np.asarray([((-1) ** h) * (label(h) ** -2) * sine(domain, freq=freq * label(h)) for h in
+        range(num_harmonics)])
+    wave = np.sum(harmonics, axis=0)
+    return wave