Optimise a value over a vector

I have been given this code below to modify to optimize the value of theta over vector (0.01,0.02, …, 0.99, 1.00) where R0=10 and D=14, any help at all would mean a lot. Thanks

errorSS<-function(epidemiology.data,N=1000000,R0,D,theta,N.time.steps=2100,delta.t=0.1){

gamma<-1/D

beta<-R0*gamma/N

S0<-theta*N

I0<-epidemiology.data$No.infected[1]

sample.index<-epidemiology.data$Time.index

S<-numeric(N.time.steps+1)

I<-numeric(N.time.steps+1)

S[1]<-S0 # Initial conditions

I[1]<-I0 # Initial conditions

for (i in 1:N.time.steps){

S[i+1]<-S[i]-beta*S[i]*I[i]*delta.t

I[i+1]<-I[i]+beta*S[i]*I[i]*delta.t-gamma*I[i]*delta.t

}

errorSS<-sum((epidemiology.data$No.infected-I[sample.index])^2)

return(errorSS)
}