[R] Optimization package

[Berend Hasselman]

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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