Displaying 2 results from an estimated 2 matches for "rkmethod".
2012 Mar 02
0
?Syntax on Taking differential on both sides of the equation in 'R'
...t;-(f*Seq1*Veq1+g*Ieq1+r*(1-Neq1)-b1*Veq1*Ieq1)/(b2+m+d+g)
Ieq1<-(-b2*Ceq1)-r*(1-Neq1)/(b1*Veq1-g-u)
Veq1<-o*(Ceq1+Ieq1)/e I want to take the differential of both sides of the equation and then solve for the inverse of the first as follows (the parameter values are made up): library(deSolve)
rkMethod("rk45dp7")
CSIeq1<-function(t,yeq1,pars) {
with (as.list(c(yeq1,pars)),{
Neq1<-Seq1+Ceq1+Ieq1
dSeq1<-d[a*(1-Neq1)/(f*Veq1+m+d)]
dCeq1<-d[(f*Seq1*Veq1+g*Ieq1+r*(1-Neq1)-b1*Veq1*Ieq1)/(b2+m+d+g)]
dIeq1<-d[(-b2*Ceq1)-r*(1-Neq1)/(b1*Veq1-g-u)]
dVeq1<-d[o*(Ceq1+Ieq1)/e]
retur...
2010 Sep 16
1
More accurate ODE solver?
Dear All,
I was using rk4 and lsoda to solve a ODE system. However, both of them gave
bad accurate solutions, especially compared with Matlab solver ODE45. For
example, ODE45 gave solutions that can go to a stable level (about 1.6) when
time goes to infinity, however, the solutions from lsoda are decreasing to
very very small (about 1e-130) numbers.
Does R have more accurate ODE solvers as