import pint
import numpy as np
import pandas as pd
from modsim import run_odeint, linspace, unpack

ureg = pint.UnitRegistry()
m = ureg.meter
s = ureg.second
kg = ureg.kilogram

init = pd.Series({'y': 381 * m, 'v': 0 * m / s})

g = 9.8 * m / s ** 2
duration = 10 * s
ts = linspace(0, duration, 11)
system = pd.Series({'init': init, 'g': g, 'ts': ts})


def slope_func(state, t, system):
    y, v = state
    dydt = v
    dvdt = -g
    return dydt, dvdt


dydt, dvdt = slope_func(init, 0, system)

run_odeint(system, slope_func)

print(system.results.head())