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# Computation of res-EWMA ARLs (mean monitoring)
x.res.ewma.arl <- function(l, c, mu, alpha=0, n=5, hs=0, r=40) {
if ( l <= 0 || l > 1 )
stop("l has to be between 0 and 1")
if ( c <= 0 )
warning("usually, c has to be positive")
if ( abs(alpha) > 1 )
warning("nonstationary AR(1) process")
if ( n < 1 )
warning("n is too small")
n <- round(n)
if ( abs(hs) > c )
warning("unusual headstart")
if ( r < 4 )
stop("r is too small")
ctyp <- 1 # later more
arl <- .C("x_res_ewma_arl",as.double(alpha),as.integer(n),
as.integer(ctyp),as.double(l),
as.double(c),as.double(hs),
as.double(mu),as.integer(r),
ans=double(length=1),PACKAGE="spc")$ans
names(arl) <- "arl"
return (arl)
}
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