58:55 +
From: Ravi Varadhan
To: "'ivo.we...@gmail.com'"
Cc: "r-help@r-project.org"
Subject: Re: [R] vectorized uni-root?
Message-ID:
<2f9ea67ef9ae1c48a147cb41be2e15c32e8...@dom-eb-mail1.win.ad.jhu.edu>
Content-Type: text/plain
Hi Ivo,
The only proble
Hi Ivo,
The only problem is that uniroot() actually uses Brent's algorithm, and is
based on the C code from netlib (there is also Fortran code available -
zeroin.f). Brent's algorithm is more sophisticated than a simple bisection
approach that you have vectorized. It combines bisection and se
hi michael---this can be done better than with outer(). A vectorized
bisection search that works with an arbitrary number of arguments is
bisection <- function(f, lower, upper, ..., numiter =100, tolerance =
.Machine$double.eps^0.25 ) {
stopifnot(length(lower) == length(upper))
flower <- f(l
On Thu, Nov 8, 2012 at 3:05 PM, ivo welch wrote:
> dear R experts--- I have (many) unidimensional root problems. think
>
> loc.of.root <- uniroot( f= function(x,a) log( exp(a) + a) + a,
> c(.,9e10), a=rnorm(1) ) $root
>
> (for some coefficients a, there won't be a solution; for others, it
> may
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