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#
# Draw a contour map of the test1 data, to show the non SPD area of
# the loglik
#
x0 <- seq(1, 3, length=20)
x1 <- -.745
sig<- seq(-2, 0, length=20)
lmat <- matrix(0, length(x0), length(sig))
for (i in 1:length(x0)) {
for (j in 1:length(sig)) {
fit<- survreg(Surv(time, status)~x, test1,
init=c(x0[i], x1, sig[j]), control=list(maxiter=0))
lmat[i,j] <- fit$loglik[1]
}
}
x1 <- -.735
lmat2 <- matrix(0, length(x0), length(sig))
for (i in 1:length(x0)) {
for (j in 1:length(sig)) {
fit<- survreg(Surv(time, status)~x, test1,
init=c(x0[i], x1, sig[j]), control=list(maxiter=0))
lmat2[i,j] <- fit$loglik[1]
}
}
clev <- -1*c(2.5,3:6, 8, 10, 15, 25)
contour(x0, sig, lmat, levels=clev)
contour(x0, sig, lmat2,levels=clev)
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