Dear Lorenzo,
You could try the BB package:
# function we need the roots for
fn1 <- function(x, a) - x^2 + x + a
# plot
curve(fn1(x, a = 5), -4, 4)
abline(h=0, col = 2)
# searching the roots in (-4, 4)
# install.packages('BB')
require(BB)
BBsolve(par = c(-1, 1), fn = fn1, a = 5)
values <- BBsolve(par = c(-1, 1), fn = fn1, a = 5)$par
values
# adding the roots to the plot
points(values, c(0, 0), pch = 8, cex = 1.1, col = 4)
HTH,
Jorge
On Sat, Sep 25, 2010 at 8:24 PM, Lorenzo Isella <> wrote:
> Dear All,
> I need to find the (possible multiple) zeros of a function f within an
> interval. I gave uniroot a try, but it just returns one zero and I need to
> provide it with an interval [a,b] such that f(a)f(b)<0.
> Is there any function to find the multiple zeros of f in (a,b) without
> constraints on the sign of f(a) and f(b)?
> Many thanks
>
> Lorenzo
>
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