Feature/speed_of_sound

pyrato/parametric.py

@@ -5,6 +5,41 @@
 """
 import numpy as np
 
+def calculate_speed_of_sound(temperature):
+    r"""Calculate the speed of sound in air depending on the temperature.
+
+    Speed of sound is calculated as [#]_.
+
+    .. math::
+        c = c_0 \sqrt{\frac{T - T_0}{20 - T_0}}
+    .. math::
+        T_0=-273.15
+    .. math::
+        c_0 = 343.2
+
+    Parameters
+    ----------
+    temperature : double
+        Temperature in degrees Celsius.
+
+    Returns
+    -------
+    speed_of_sound : double
+        Speed of sound in m/s.
+
+    References
+    ----------
+    .. [#] ISO 9613-1 (Formula A.5)
+    """
+    if temperature < -273.15:
+        raise ValueError(
+            "Temperature must be greater than absolute zero (-273.15 °C).")
+    T_0 = -273.15
+    c_0 = 343.2
+    speed_of_sound = c_0 * np.sqrt((temperature - T_0)/(20 - T_0))
+    return speed_of_sound
+
+
 def energy_decay_curve_analytic(
         surfaces, alphas, volume, times, source=None,
         receiver=None, method='eyring', c=343.4, frequency=None,

tests/test_speed_of_sound.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""Tests for reverberation time related things."""
+import numpy as np
+import numpy.testing as npt
+
+import pyrato as ra
+import pytest
+
+@pytest.mark.parametrize('T',[0,20,1000])
+def test_speed_of_sound(T):
+    speed=ra.parametric.calculate_speed_of_sound(T)
+    assert isinstance(T, (int, float))
+    npt.assert_allclose(speed, 343.2 * np.sqrt((T + 273.15) / 293.15))
+    with pytest.raises(ValueError,match=
+                       "Temperature must be greater than absolute zero"):
+        ra.parametric.calculate_speed_of_sound(-300)