[R] Optimization package
Berend Hasselman
bhh at xs4all.nl
Thu Sep 15 07:56:31 CEST 2011
Diviya Smith wrote:
>
> Hi there,
>
> I have a complex math equation which does not have a closed form solution.
> It is -
>
> y <- (p*exp(-a*d)*(1-exp((d-p)*(a-x[1]))))/((p-d)*(1-exp(-p*(a-x[1]))))
>
> For this equation, I have all the values except for x[1]. So I need to
> solve
> this problem numerically. Can anyone suggest an optimization package that
> I
> can use to estimate the value for x[1]?
>
So you have data for : a, d, p and y?
Define a function
f <- function(x) y -
(p*exp(-a*d)*(1-exp((d-p)*(a-x))))/((p-d)*(1-exp(-p*(a-x))))
and use uniroot to solve f(x) = 0 and set x[1] to the root found by uniroot.
/Berend
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