# [R] uniroot

Uwe Ligges ligges at statistik.uni-dortmund.de
Sun Jul 30 12:22:13 CEST 2006

```nurza m wrote:
> Hello,
>
> I am struggling to find the root of a exponent
> function.
> "uniroot" is complaining about a values at end points
> not of opposite sign?

And you think it is not the case? Why?
We cannot help because you have not given a reproducible example (What
is w and gp?), which the posting guide asks you to do.

including some blanks and without all those ">" and "+":

saeqn <- function(s, l)
{
p <- exp(-l\$gp\$lambda + s) * l\$gp\$c
k11 <- (l\$gp\$mu * (l\$gp\$lambda^2) * l\$gp\$c -
s * l\$gp\$lambda * l\$gp\$c * l\$gp\$mu +
l\$gp\$mu * l\$gp\$lambda) * p
k12 <- -l\$gp\$mu * l\$gp\$lambda -
s^2 + 2 * s * l\$gp\$lambda - (l\$gp\$lambda^2)
k13 <- k11 + k12
k14 <- (l\$gp\$lambda - s) *
(-l\$gp\$mu * s - s * l\$gp\$lambda + s^2 +
l\$gp\$mu * l\$gp\$lambda * p)
k1 <- -k13 / k14
k1 - l\$t
}

s <- sapply(seq(along = w), function(i) {
uniroot(saeqn, lower = -5000, upper = 0.01036597923,
l = list(t = w[i], gp = gp))\$root
}
)

>
> s<- sapply(1:length(w),function(i)
> +  {
> +
> + +
> +
> +
> uniroot(saeqn,lower=-5000,upper=0.01036597923,l=list(t=w[i],gp=gp))\$root
> +  })
> Error in uniroot(saeqn, lower = -5000, upper =
> 0.01036597923, l = list(t = w[i],  :
>         f() values at end points not of opposite sign
>
>
>
>
> and here is my fonction "saeqn".
>
>
>
>>saeqn<-function(s,l)
>
> +  {
> +
> +
> + p<- exp(-l\$gp\$lambda+s)*l\$gp\$c
> +
> +
> +
> k11<-(l\$gp\$mu*(l\$gp\$lambda^2)*l\$gp\$c-s*l\$gp\$lambda*l\$gp\$c*l\$gp\$mu+l\$gp\$mu*l\$gp\$lambda)*p
> +
> + k12 <-
> -l\$gp\$mu*l\$gp\$lambda-s^2+2*s*l\$gp\$lambda-(l\$gp\$lambda^2)
> +
> + k13 <-k11+k12
> +
> +
> k14<-(l\$gp\$lambda-s)*(-l\$gp\$mu*s-s*l\$gp\$lambda+s^2+l\$gp\$mu*l\$gp\$lambda*p)
> +
> + k1<- -k13/k14
> +
> +  k1-l\$t
> +  }
>
>
>
> . There is something I must be missing since I never
> luck with "uniroot"!
>
> Thanks,
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help