```
## CHEBFUN example by Trefethen
f <- function(x) exp(x)*sin(3*x)*tanh(5*cos(30*x))
fminbnd(f, -1, 1) # fourth local minimum (from left)
g <- function(x) complexstep(f, x) # complex-step derivative
xs <- findzeros(g, -1, 1) # local minima and maxima
ys <- f(xs); n0 <- which.min(ys) # index of global minimum
fminbnd(f, xs[n0-1], xs[n0+1]) # xmin:0.7036632, fmin: -1.727377
## Not run:
# ezplot(f, -1, 1, n = 1000, col = "darkblue", lwd = 2)
# ezplot(function(x) g(x)/150, -1, 1, n = 1000, col = "darkred", add = TRUE)
# grid()## End(Not run)
```

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