Sort sensitivity frequencies in __post_init__ #439

Needed so that np.interp in sensitivity_at_frequency produces correct results.

Author: ebrahimebrahim

src/openlifu/xdc/element.py

@@ -11,6 +11,7 @@
 
 
 def sensitivity_at_frequency(sensitivity: float | List[tuple[float, float]], frequency: float) -> float:
+    """Return sensitivity at `frequency`; list form assumes frequencies are sorted ascending."""
     if isinstance(sensitivity, list):
         freqs, values = zip(*sensitivity)
         return float(np.interp(frequency, freqs, values))
@@ -85,7 +86,7 @@ def __post_init__(self):
         if self.sensitivity is None:
             self.sensitivity = 1.0
         elif isinstance(self.sensitivity, list):
-            self.sensitivity = [(float(f), float(v)) for f, v in self.sensitivity]
+            self.sensitivity = sorted(((float(f), float(v)) for f, v in self.sensitivity), key=lambda t: t[0])
 
     @property
     def x(self):

src/openlifu/xdc/transducer.py

@@ -105,7 +105,7 @@ def __post_init__(self):
         if self.sensitivity is None:
             self.sensitivity = 1.0
         elif isinstance(self.sensitivity, list):
-            self.sensitivity = [(float(f), float(v)) for f, v in self.sensitivity]
+            self.sensitivity = sorted(((float(f), float(v)) for f, v in self.sensitivity), key=lambda t: t[0])
 
     def calc_output(self, cycles: float, frequency: float, dt: float, delays: np.ndarray = None, apod: np.ndarray = None, amplitude: float = 1.0) -> np.ndarray:
         if delays is None: