Problem making simple loop

[Jesper Hybel]

Hello

I'm completely new to C++ and only use it through R. Anyway I'm trying to make a loop - since looping in R is rather inefficient:

cppFunction('

	
	NumericMatrix sim(NumericMatrix Z, double sigma_0,long double delta,long double omega,long double gamma){
		int nrow=Z.nrow(), ncol=Z.ncol();
		NumericMatrix out(nrow,ncol);
		
	for (int q=0; q<ncol; q++) {out(0,q)=sigma_0;
						}
	for (int i=0; i<ncol; i++){

		for (int j=1; j<nrow; j++){
		long double z=Z(j-1,i);
		long double sigma=out(j-1,i);
		long double e=z*sigma;
		long double w=abs(e)-gamma*e;
		out(j,i)=w;		

		}
		}
	
	
	return out;
}
')

this should give me a function in R that is executed in C++ and then I give it a matrix Z and some arguments - so this is what I type in R:

Z<-matrix(1:12,nrow=4,byrow=TRUE)
sim(Z, sigma_0=9,delta=0.5,omega=4,gamma=0.5)

everything works out fine except for the last spot in the returned matrix giving me a result of 181.75 which should have been

abs(40.5*9)-0.5*9*40.5=182.25