R Under development (unstable) (2023-12-07 r85661 ucrt) -- "Unsuffered Consequences"
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> x <- runif(10)
> y <- 1+x+rnorm(10,sd=0.1)
> d <- data.frame(x,y)
> 
> library(bbmle)
Loading required package: stats4
> m1 <- mle2(y~dnorm(a+b*x,sd=exp(s)),start=list(a=1,b=1,s=log(0.1)),data=d)
> 
> m2 <- mle2(y~dnorm(a+b*x,sd=exp(s)),start=list(a=1,b=1,s=log(0.1)),
+   method="L-BFGS-B",lower=c(a=0,b=0,s=-Inf),data=d)
> 
> m2F <- mle2(y~dnorm(a+b*x,sd=exp(s)),start=list(a=1,b=1,s=log(0.1)),
+   method="L-BFGS-B",lower=c(a=0,b=0,s=-Inf),
+   fixed=list(a=1),data=d)
Warning messages:
1: In mle2(y ~ dnorm(a + b * x, sd = exp(s)), start = list(a = 1, b = 1,  :
  length mismatch between lower/upper and number of non-fixed parameters: # lower=3, # upper=0, # non-fixed=2
2: In oout$par == call$lower :
  longer object length is not a multiple of shorter object length
3: In mle2(y ~ dnorm(a + b * x, sd = exp(s)), start = list(a = 1, b = 1,  :
  some parameters are on the boundary: variance-covariance calculations based on Hessian may be unreliable
> 
> 
> proc.time()
   user  system elapsed 
   1.50    0.12    1.60