XDemoAutoC <-
function( UseData, OutLength = -999, PlotToggle = FALSE) {
if (OutLength == -999) {
    OutLength = floor(length(UseData) / 4);
}
#### Now call to .C()
OutPut =.C("DemoAutoCor", OutVec=as.double( vector("numeric", OutLength) ),
OutLength = as.integer(OutLength),
InputVector = as.double(UseData),
InputLength = as.integer(length(UseData))
);
if(PlotToggle == TRUE) {
xxxn = 0:(length(OutPut$OutVec)-1);
plot(OutPut$OutVec~xxxn, type="n", main="Autocorrelation Estimates");
for (ii in 1:length(xxxn)) {
lines( c(0, OutPut$OutVec[ii])~c(xxxn[ii], xxxn[ii]), lwd=3, col="black" );
}
}
return(OutPut$OutVec)
}