```
# options(digits=15)
f <- function(x) x * cos(0.1*exp(x)) * sin(0.1*pi*exp(x))
quad(f, 0, 4) # 1.2821290747821
quad(f, 0, 4, tol=10^-15) # 1.2821290743501
integrate(f, 0, 4)
# 1.28212907435010 with absolute error < 4.1e-06
## Not run:
# xx <- seq(0, 4, length.out = 200)
# yy <- f(xx)
# plot(xx, yy, type = 'l')
# grid()## End(Not run)
```

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