[R] optimize in very small values

Uwe Ligges ligges at statistik.uni-dortmund.de
Tue Nov 23 09:32:49 CET 2004

Troels Ring wrote:

> I hope you will forgive me this simple question on titration.
> I'm trying to find very small values from the algorithm below, which I 
> believe is
> correctly formatted, and the constants are also correct. When SID goes 
> over ATOT, fitted vales are
> much too low compared to the literature. I guess I must be using 
> optimize in a wrong way but cannot find out how to improve it. I'm on 
> windows, R 2.0. Best wishes
> Troels Ring, Aalborg
> ATOT <- 0.019
> KA <- 3e-7
> KW <- 4.4e-14
> SID <- 0.01
> ff <- function(H,KA,SID,ATOT)
> {H^3 + (KA+SID)*H^2+(KA*(SID-ATOT)-KW)*H- KA*KW}
> -log10(optimize(ff,c(0,.1),tol=.Machine$double.eps,KA=KA,SID=SID,ATOT=ATOT)$minimum) 

Well, whether the usage is appropriate depends on the problem. At least 
I have not understood what you are going to minimize...

Uwe Ligges

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