period,phase_velocity
 25, 3.4332732
 27, 3.5354295
 30, 3.6453763
 32, 3.6725123
 35, 3.7236551
 37, 3.7407297
 40, 3.8061471
 45, 3.8409928
 50, 3.8584334
 55, 3.8724791
 60, 3.8843613
 70, 3.9292868
 80, 3.9615701
 90, 4.0004396
100, 4.0443201
130, 4.1755289
150, 4.2565493
199, 4.5270584