# python
import os
import math
p=80.0 # percent
t=1.0 # seconds
R=1.0 # resistance
L=t/math.log(100/(100-p), math.exp(1))
l=L*R # inductance
print('l =', round(l*1000, 3), 'mH')
p=p
R=R
L=l/R
t=L*math.log(100/(100-p))
print('t =', round(t, 3), 's')
t=t
R=R
L=l/R
p=100-100/math.pow(math.exp(1), t/L)
print('p =', round(p, 3), '%')
