Hi John,
SU is definitely full of unknown resources !!!
I hope everyone is as fine as possible, in these difficult times...
D.
PS
Don't forget that
wiki.seismic-unix.org needs contributions !!!!
Ask me for an account to write in the wiki...
Le 05/04/2020 à 20:38, John Stockwell a écrit :
I send my good wishes to all of you and I hope that you, your
families, and your friends are faring well in this difficult time.
For those who are interested in modeling populations, such as the
current epidemic, there is a logistic equation solver called
“verhulst” in the SU package which you may find of interest.
For example for Covid-19 cases in the US, taking 22 January as day 0
of cases in the US and 29 February as day 0 for deaths. Respective
stepmax= values of 72 for cases and 34 for deaths are both 3 April
verhulst stepmax=72 h=1 a1=.176 y0=1 a2=1e7 mode=x > calculated_cases.bin
verhulst stepmax=35 h=1 a1=.268 y0=1 a2=1e6 mode=x > calculated_deaths.bin
xgraph < calculated_cases.bin n=72 nplot=1 d1=1 &
xgraph < calculated_deaths.bin n=34 nplot=1 d1=1 &
The growth rate a1 values are determined empirically from publicly
available data, in this case from the CDC and from the Worldometer
site. You will have to make your own estimate of a1 for the data that
you are modeling.
Another parameter that is harder to get is an estimate of the carrying
capacity of the system a2. Here I am assuming a maximum of 1 million
cases in the US and 100 thousand deaths.
The number of new cases or deaths per day is measured by the
derivative of the solutions to the verhulst equation
verhulst stepmax=72 h=1 a1=.176 y0=1 a2=1e7 mode=y > delta_cases.bin
verhulst stepmax=35 h=1 a1=.268 y0=1 a2=1e6 mode=y > delta_deaths.bin
xgraph < delta_cases.bin n=72 nplot=1 d1=1 &
xgraph < delta_deaths.bin n=34 nplot=1 d1=1 &
The peak in the change of the population per day occurs when the
population reaches the exactly half of the carrying capacity of the
system. Thus, raising the carrying capacity will increase the height
of the peak and move it out later in time.
Take care, everyone and stay safe.
-John
John Stockwell
Visit:
https://wiki.Seismic-Unix.org
The new home of Seismic Un*x
_______________________________________________
Seisunix mailing list
Seisunix(a)mailman.seismic-unix.org
https://mailman.seismic-unix.org/listinfo/seisunix
--
|Dominique Rousset LFCR UMR5150 / E2S UPPA / Dpt des géosciences|
|Univ. Pau et des Pays de l'Adour BP 1155 F-64013 Pau Cedex - France|
|mailto:dominique.rousset@univ-pau.fr jami:drousset
http://lfc.univ-pau.fr|
|Off: +33 559 407 423|Cell: +33 660 861 391|xmpp: dominique(a)rousset.nom.fr|