error "Non numeric argument to binary operator"

General
1

Hello,
I'm getting the error "Non numeric argument to binary operator" with this code :

SDO <- function(t,state,parms)
{
  with(as.list(c(state,parms)),
       {
          a=parms[1]; b= parms[2];c=parms[3];d=parms[4]; b_1= parms[5]; b_2= parms[6]; b_3= parms[7]
          R = state["R"] ; S=as.numeric(state["S"])
          dR <- a-d*((S/b)^c/(1+(S/b)^c)) - b_1*R
          dS <- b_2*R - b_3*S
          return(list(c(dR, dS)))
       }
  )
}
a=3
b=2
c=1.5
d=1
b_1 = 1
b_2 = 2
b_3 = 3

parameters = list(a=a, b=b, c=c,d=d, b_1=b_1, b_2=b_2, b_3=b_3)
R0 = 30
S0 = 10
#
yini <- c(R=R0,S=S0) # Point de depart
#
times <- seq(0,0.5,by=0.0001)
out <- ode(y=yini,times=times,func=SDO,parms=parameters,method="lsoda")

Error in S/b : argument non numérique pour un opérateur binaire

Where is the problem ?

2 
  a=parms[1]; b= parms[2];c=parms[3];d=parms[4]; b_1= parms[5]; b_2= parms[6]; b_3= parms[7]

should be

  a=parms[[1]]; b= parms[[2]];c=parms[[3]];d=parms[[4]]; b_1= parms[[5]]; b_2= parms[[6]]; b_3= parms[[7]]

to fully unpack from list, otherwise you will be doing arithmetic on lists rathers than numerics

3

Merciiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
Thank you

4

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