Thursday, April 23, 2020

SIR with Sage

Very simple implementation of the SIR epidemic model using Sage
mathematical framework.
# Infected
IInit = 1
# Susceptible
SInit = N - IInit
# Resistant
RInit = 0
# Transmission rate
betaInit = 0.5
# Transmission rate attenuation
delta = 0.01
# Recovery rate
gamma = 0.1
# Population size
N = 10000
# End time
tMax = 100
# Number of points
points = 1000

# Standard SIR model
def ODE_RHS(t, Y):
  (S, I, R, beta) = Y    
  dS = - beta * S * I / N
  dI = beta * S * I / N - gamma * I
  dR = gamma * I
  dbeta = - beta * delta
  return (dS, dI, dR, dbeta)

# Set up numerical solution of ODE
solver = ode_solver(function = ODE_RHS,
                    y_0 = (SInit, IInit, RInit, betaInit),
                    t_span = (0, tMax),
                    algorithm = 'rk8pd')

# Numerically solve
solver.ode_solve(num_points = points)

# Plot solution
show(plot(solver.interpolate_solution(i = 0), 0, tMax, legend_label = 'S(t)', color = 'green')
   + plot(solver.interpolate_solution(i = 1), 0, tMax, legend_label = 'I(t)', color = 'red')
   + plot(solver.interpolate_solution(i = 2), 0, tMax, legend_label = 'R(t)', color = 'blue')) 


Wednesday, April 22, 2020

Sigmoidal Fit

When I do extremely naive sigmoidal fit to the evolution of the number of virus victims in France, I get about the same prevision as prof.Raoult - that the epidemie will end very soon.
This can mean two things:
- Either I'm as clever as prof.Raoult.
- Or the other way.

Thursday, April 9, 2020

We Will Win

We will win. When we concentrate, we can do almost anything - land on the Moon, control nuclear power, destroy the virus. And we will do it much faster than ever in history - thanks to the globalization.

The economy will reboot faster than most expect. This is not an economical crisis. Once all is over, we will travel more than ever, we will produce more then ever. We will create a big debt - and we will pay it by the inflation. Which is not a bad thing, inflation means that the rich pay more then others.

The only real danger are those people, lobbies and activists, who want to use the problems to pass their demagogic agenda, which they have failed to pass by the democratic means. We should not let them to profit from the crises.

Monday, April 6, 2020

Not the end

Now this is not the end.
It is not even the beginning of the end.
But it is, perhaps, the end of the beginning.