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yrfun<-function(Fmult,M,sa,wa){
Fmort<-Fmult*sa
Z<-Fmort+M
prop<-(Fmort/Z)*(1-exp(-Z))
Ztemp<-c(0,Z[1:(length(Z)-1)])
cumZ<-exp(-cumsum(Ztemp))
C<-prop*cumZ
Y<-sum(wa*C)
return(Y)
}
srfun<-function(Fmult,M,sa,wa,pa){
Fmort<-Fmult*sa
Z<-Fmort+M
Ztemp<-c(0,Z[1:(length(Z)-1)])
cumZ<-exp(-cumsum(Ztemp))
S<-sum(wa*pa*cumZ)
return(S)
}
project<-function(Nhist,Fmort,sa,M,wa,alpha,K){
N0<-Nhist*exp(rnorm(1)*CV.N) # Rather silly - everything has the same CV etc
Ytraj<-c()
Straj<-c()
for(y in years){
Fimplem<-Fmort*exp(rnorm(1)*CV.pred) # Implementation error
Z<-Fimplem*sa+M
C<-(Fimplem*sa/Z)*(1-exp(-Z))*N0
S<-sum(wa*pa*N0)
R<-(alpha*S/(1+S/K))*exp(rnorm(1)*CV.R) # Recr with variation
#R<-(alpha*S/(1+S/K)) # Recr without variation
N1<-N0*exp(-Z)
N0<-c(R,N1[1:(length(N1)-1)])
Ytraj<-c(Ytraj,sum(wa*C))
Straj<-c(Straj,S)
}
return(list(Y=Ytraj,S=Straj))
}