R Under development (unstable) (2026-02-09 r89390 ucrt) -- "Unsuffered Consequences"
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Platform: x86_64-w64-mingw32/x64

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> 
>  objfun <- function(x) {
+      ##### Rosenbrock's function #####
+      stopifnot(is.numeric(x))
+      stopifnot(length(x) == 2)
+      f <- expression(100 * (x2 - x1^2)^2 + (1 - x1)^2)
+      g1 <- D(f, "x1")
+      g2 <- D(f, "x2")
+      h11 <- D(g1, "x1")
+      h12 <- D(g1, "x2")
+      h22 <- D(g2, "x2")
+      x1 <- x[1]
+      x2 <- x[2]
+      f <- eval(f)
+      g <- c(eval(g1), eval(g2))
+      B <- rbind(c(eval(h11), eval(h12)), c(eval(h12), eval(h22)))
+      list(value = f, gradient = g, hessian = B)
+  }
> 
>  library(trust)
> 
>  tout <- trust(objfun, c(3, 1), 1, 5, blather = TRUE)
>  tout
$value
[1] 5.160801e-15

$gradient
[1]  5.430221e-07 -2.003744e-07

$hessian
          [,1] [,2]
[1,]  802.0001 -400
[2,] -400.0000  200

$argument
[1] 1 1

$converged
[1] TRUE

$iterations
[1] 21

$argpath
          [,1]     [,2]
 [1,] 3.000000 1.000000
 [2,] 2.213163 1.617161
 [3,] 1.995363 3.605266
 [4,] 1.982307 3.929371
 [5,] 1.982307 3.929371
 [6,] 1.982307 3.929371
 [7,] 1.920608 3.687103
 [8,] 1.793795 3.203451
 [9,] 1.587591 2.477924
[10,] 1.525765 2.324137
[11,] 1.525765 2.324137
[12,] 1.446444 2.087048
[13,] 1.281393 1.615071
[14,] 1.237286 1.528931
[15,] 1.237286 1.528931
[16,] 1.189572 1.413397
[17,] 1.092024 1.183211
[18,] 1.059858 1.122264
[19,] 1.010263 1.018171
[20,] 1.003384 1.006732
[21,] 1.000032 1.000052

$argtry
          [,1]      [,2]
 [1,] 2.213163 1.6171606
 [2,] 1.995363 3.6052660
 [3,] 1.982307 3.9293710
 [4,] 1.032382 0.1634548
 [5,] 1.737285 2.9598532
 [6,] 1.920608 3.6871035
 [7,] 1.793795 3.2034513
 [8,] 1.587591 2.4779236
 [9,] 1.525765 2.3241367
[10,] 1.227793 1.4186882
[11,] 1.446444 2.0870482
[12,] 1.281393 1.6150706
[13,] 1.237286 1.5289305
[14,] 1.066466 1.1081695
[15,] 1.189572 1.4133965
[16,] 1.092024 1.1832113
[17,] 1.059858 1.1222640
[18,] 1.010263 1.0181710
[19,] 1.003384 1.0067320
[20,] 1.000032 1.0000522
[21,] 1.000000 1.0000001

$steptype
 [1] "easy-easy" "easy-easy" "Newton"    "Newton"    "easy-easy" "easy-easy"
 [7] "easy-easy" "Newton"    "Newton"    "Newton"    "easy-easy" "easy-easy"
[13] "Newton"    "Newton"    "easy-easy" "easy-easy" "Newton"    "Newton"   
[19] "Newton"    "Newton"    "Newton"   

$accept
 [1]  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE
[13]  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE

$r
 [1] 1.000 2.000 4.000 4.000 1.000 0.250 0.500 1.000 1.000 1.000 0.250 0.500
[13] 0.500 0.500 0.125 0.250 0.500 0.500 0.500 0.500 0.500

$rho
 [1]   1.1323840   1.0268439   1.0009051 -86.2278968   0.1941958   1.0028937
 [7]   0.9305907   0.6758818   1.1429810  -3.5561846   1.0310304   0.5325419
[13]   1.1190080  -0.8036577   1.0321407   0.7780458   1.1565171   0.9687805
[19]   1.0341229   1.0081017   1.0001652

$valpath
 [1] 6.404000e+03 1.077921e+03 1.514382e+01 9.649301e-01 9.649301e-01
 [6] 9.649301e-01 8.477839e-01 6.504098e-01 5.260586e-01 2.778900e-01
[11] 2.778900e-01 2.019671e-01 1.515350e-01 5.668301e-02 5.668301e-02
[16] 3.622117e-02 1.712582e-02 3.690009e-03 7.103242e-04 1.167477e-05
[21] 1.363381e-08

$valtry
 [1] 1.077921e+03 1.514382e+01 9.649301e-01 8.142600e+01 8.835630e-01
 [6] 8.477839e-01 6.504098e-01 5.260586e-01 2.778900e-01 8.402095e-01
[11] 2.019671e-01 1.515350e-01 5.668301e-02 8.956198e-02 3.622117e-02
[16] 1.712582e-02 3.690009e-03 7.103242e-04 1.167477e-05 1.363381e-08
[21] 5.160801e-15

$preddiff
 [1] -4.703421e+03 -1.034994e+03 -1.416607e+01 -9.331211e-01 -4.189951e-01
 [6] -1.168082e-01 -2.120955e-01 -1.839836e-01 -2.171240e-01 -1.581244e-01
[11] -7.363787e-02 -9.470083e-02 -8.476432e-02 -4.091166e-02 -1.982466e-02
[16] -2.454271e-02 -1.161748e-02 -3.075707e-03 -6.755962e-04 -1.156742e-05
[21] -1.363155e-08

$stepnorm
 [1] 1.000000e+00 2.000000e+00 3.243678e-01 3.883875e+00 1.000000e+00
 [6] 2.500007e-01 5.000010e-01 7.542615e-01 1.657492e-01 9.532179e-01
[11] 2.500056e-01 5.000045e-01 9.677608e-02 4.541137e-01 1.249989e-01
[16] 2.500017e-01 6.891465e-02 1.153040e-01 1.334802e-02 7.473704e-03
[21] 6.093529e-05

> 
>  (tout$stepnorm / tout$r)[tout$accept & tout$steptype != "Newton"]
[1] 1.0000000 1.0000000 1.0000030 1.0000019 1.0000224 1.0000091 0.9999912
[8] 1.0000067
> 
> 
> proc.time()
   user  system elapsed 
   0.10    0.09    0.18