"""Mode frequencies from the stiffness written by modes.ts.

Usage: python3 modes.py K.bin META.json [fmax]
Prints the frequencies (Hz) of the modes below fmax, excluding the six rigid modes.
"""
import sys, json, numpy as np

K = np.fromfile(sys.argv[1], dtype="<f8")
meta = json.load(open(sys.argv[2]))
n = meta["n"]
K = K.reshape(n, n)
K = 0.5 * (K + K.T)
ev = np.linalg.eigvalsh(K)
f = np.sqrt(np.clip(ev, 0, None)) / (2 * np.pi)
fmax = float(sys.argv[3]) if len(sys.argv) > 3 else 1500
modes = f[(f > 5) & (f < fmax)]
print(json.dumps({"params": meta["params"], "modes": [round(float(v), 1) for v in modes]}))