y1 = [0.0, 13.99, 27.99, 41.98, 55.98, 69.97, 83.97, 97.97, 111.96, 125.96,
    139.95, 153.95]
new_length = 25
new_x = np.linspace(x.min(), x.max(), new_length)
new_y = sp.interpolate.interp1d(x, y, kind='cubic')(new_x)
Сплайн-интерполяция с Python