[R] glm cannot find valid starting values

[Ronaldo ReisJunior]

Hi,

I have some similar problems. Some times ago this problem dont there existed.

Look this simple example:

> Y <- c(0,0,0,1,4,8,16)
> X <- c(1,2,3,4,5,6,7)

> m <- glm(Y~X,family=gaussian(link=log))
Error in eval(expr, envir, enclos) : cannot find valid starting values: please 
specify some

> m <- glm(Y~X,family=gaussian(link="log"))
Error in eval(expr, envir, enclos) : cannot find valid starting values: please 
specify some

What is the problem? I think that the problem is with the log link algorithm 
and zeros.

Look

> Y <- c(0,0.1,0.5,1,4,8,16)

> m <- glm(Y~X,family=gaussian(link="log"))
Error in eval(expr, envir, enclos) : cannot find valid starting values: please 
specify some
 
> Y <- c(0.01,0.1,0.5,1,4,8,16)
 
> m <- glm(Y~X,family=gaussian(link="log"))

Without Zeros it work.

It is a real bug?

Thanks
Ronaldo
-- 
Preserve wildlife -- pickle a squirrel today!
--
> Prof. Ronaldo Reis Júnior
|  .''`. UNIMONTES/Depto. Biologia Geral/Lab. Ecologia Evolutiva
| : :'  : Campus Universitário Prof. Darcy Ribeiro, Vila Mauricéia
| `. `'` CP: 126, CEP: 39401-089, Montes Claros - MG - Brasil
|   `- Fone: (38) 3229-8190 | chrysopa em gmail.com
| ICQ#: 5692561 | LinuxUser#: 205366