; From Hannah Slater, 2016-02-05
METHOD RK4

STARTTIME = 0
STOPTIME=100
DT = 0.01
YEARS = TIME

d/dt( S ) = Births - b*S - beta*S*I/N + delta*R
d/dt( I ) = beta*S*I/N - (b+sigma)*I
d/dt( R ) = sigma*I - b*R-delta*R

init S = N - I0
init I = I0
init R = 0

Births = N/75
b = 1/75
N = 1e7
I0 = 1
beta = 24
sigma = 12
delta = 1/5
