```
# make some dummy data
tdata <- data.frame(x= lung$age, y = 10*log(lung$age-35) + rnorm(228, 0, 2))
fit1 <- lm(y ~ -1 + nsk(x, df=4, intercept=TRUE) , data=tdata)
fit2 <- lm(y ~ nsk(x, df=3), data=tdata)
# the knots (same for both fits)
knots <- unlist(attributes(fit1$model[[2]])[c('Boundary.knots', 'knots')])
sort(unname(knots))
unname(coef(fit1)) # predictions at the knot points
unname(coef(fit1)[-1] - coef(fit1)[1]) # differences: yhat[2:4] - yhat[1]
unname(coef(fit2))[-1] # ditto
if (FALSE) {
plot(y ~ x, data=tdata)
points(sort(knots), coef(fit1), col=2, pch=19)
coef(fit)[1] + c(0, coef(fit)[-1])
}
```

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