```
# Fitting the sine function by a polynomial
x <- seq(0, pi, length.out=25)
y <- sin(x)
p <- polyfit(x, y, 6)
## Not run:
# # Plot sin and fitted polynomial
# plot(x, y, type="b")
# yf <- polyval(p, x)
# lines(x, yf, col="red")
# grid()## End(Not run)
## Not run:
# n <- 3
# N <- 100
# x <- linspace(0, 2*pi, N); y = sin(x) + 0.1*rnorm(N)
# xfix <- c(0, 2*pi); yfix = c(0, 0)
#
# xs <- linspace(0, 2*pi); ys <- sin(xs)
# plot(xs, ys, type = 'l', col = "gray",
# main = "Polynom Approximation of Degree 3")
# grid()
# points(x, y, pch='o', cex=0.5)
# points(xfix, yfix, col = "darkred")
#
# p0 <- polyfit(x, y, n)
# lines(xs, polyval(p0, xs), col = "blue")
#
# p1 <- polyfix(x, y, n, xfix, yfix)
# lines(xs, polyval(p1, xs), col = "red")
#
# legend(4, 1, c("sin", "polyfit", "polyfix"),
# col=c("gray", "blue", "red"), lty=c(1,1,1))## End(Not run)
```

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