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2017-10-19 09:37:54 -0600 | asked a question | Graphing ineqalities So I'm trying to graph the inequality x+y+3u>=0 I want to keep the u fixed, but I'm having issues finding out how to do that. Also, I was wondering if it would be possible to have some type of dynamic slider for u, so that this way I can change the value of u. |

2017-09-17 17:05:33 -0600 | asked a question | Rewrite equilibrium variables in terms of another variable I'm wondering how to replace the equilibrium variables in terms of another one. I want the equilibrium to be in terms of a new varible called R = beta*o/(u+y)(u+o) and I can't seem to find the right function that would allow me to do this. Equilibrium point: S= (u+y)(u+o)/beta*o Want: S = 1/R |

2017-02-16 15:17:29 -0600 | asked a question | ValueError: error solving I don't understand stand why sagemath says that there is a error solving when it solves the differential equations just fine without the beta_h * S *H in the equations. Any ideas? ## Population sizeN = 10 ## Initial infectionsIInit = 1 HInit = 1 EInit = 1 SInit = 7 RInit = 0 beta = .1 alpha = .1 gamma_h = .3 gamma_ih = .1 gamma_1 =.2 theta = .2 delta = .1 delta_2 = .2 delta_1 = .1 gamma = .1 ## End timetMax = 10 ## Standard SIR modeldef ODE_RHS(t, Y): (S, I, E, H, R) = Y ## Set up numerical solution of ODEsolver = ode_solver(function = ODE_RHS, y_0 = (SInit, IInit, EInit, HInit, RInit), t_span = (0, tMax), algorithm = 'rk8pd') ## Numerically solvesolver.ode_solve(num_points = 1) ## Plot solutionshow( plot(solver.interpolate_solution(i = 0), 0, tMax, legend_label = 'S(t)', color = 'green') + plot(solver.interpolate_solution(i = 2), 0, tMax, legend_label = 'I(t)', color = 'red') + plot(solver.interpolate_solution(i = 4), 0, tMax, legend_label = 'R(t)', color = 'blue') + plot(solver.interpolate_solution(i = 1), 0, tMax, legend_label = 'E(t)', color = 'pink') + plot(solver.interpolate_solution(i = 3), 0, tMax, legend_label = 'H(t)', color = 'black') ) |

2017-01-14 20:44:20 -0600 | asked a question | plot point color change How do change the plot point color so that I can tell the difference between my three different equations? Here is what I have so far: |

2016-12-09 20:54:33 -0600 | received badge | ● Editor (source) |

2016-12-09 20:35:40 -0600 | asked a question | SIR desolve_system 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]? |

2016-11-20 06:11:18 -0600 | received badge | ● Student (source) |

2016-11-20 05:44:17 -0600 | asked a question | Epidemiology equilibria solved, but what happened?? var('beta gamma S I R N') dS = - beta * S * I / N dI = beta * S * I / N - gamma * I dR = gamma * I solve([dS == 0, dI == 0, dR == 0], [S, I, R]) [[S == r7, I == 0, R == r8]] Why am i getting different values for S and R which correlate to how many times I run the code? At first I thought that it was because I did an interpolate above, but when I went and modified the code a bit at the beginning I was still left with increasing equilibria values. the next run will be [[S == r9, I == 0, R == r10]] Does anyone know why this is happening?? |

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