SIR desolve_system

asked 2016-12-09 20:35:40 -0500

kaylavb23 gravatar image

updated 2016-12-09 20:54:33 -0500

var('beta gamma S I R N') dS = - beta * S * I /N dI = beta * S * I / N - gamma * I dR = gamma * I

equilibria = solve([dS, dI, dR], [S, I, R]) show(equilibria) solve([dS == 0, dI == 0, dR == 0], [S, I])

and the output is [[S == r76, I == 0, R == r77]] but I know that there is a second one with S == 0, I == 0 and R == 0. I have tried using desolve_system in the hopes that it prints out both answers but it asks for the ivar and I need it to solve both S and I. Is there some other way or command that I can use where sage will give me both [S == r1, I == 0, R == r1] and [ S == I == R == 0]?

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Comments

But r76 and r77 are just saying that S and R are arbitrary, including $0$. So there are no missing solutions, right? PS: you can display your code properly by selecting it and pressing the "101010" button in edit mode.

mforets gravatar imagemforets ( 2016-12-10 03:54:16 -0500 )edit

The answer provided in https://ask.sagemath.org/question/356... still applies.

tmonteil gravatar imagetmonteil ( 2016-12-10 04:33:27 -0500 )edit