ugh-optim

ugh-optim.md

## requires pass by position?

fr_pos <- function(x) {   ## Rosenbrock Banana function
    x1 <- x[1]
    x2 <- x[2]
    100 * (x2 - x1 * x1)^2 + (1 - x1)^2
}

pars <- list(a = -1.2, b = 1)
pars$a
#> [1] -1.2
optim(pars, fr_pos)
#> $par
#>        a        b 
#> 1.000260 1.000506 
#> 
#> $value
#> [1] 8.825241e-08
#> 
#> $counts
#> function gradient 
#>      195       NA 
#> 
#> $convergence
#> [1] 0
#> 
#> $message
#> NULL

fr_list <- function(x) {   ## Rosenbrock Banana function
    x1 <- x$a
    x2 <- x$b
    100 * (x2 - x1 * x1)^2 + (1 - x1)^2
}

pars <- list(a = -1.2, b = 1)

optim(pars, fr_list)
#> Error in x$a: $ operator is invalid for atomic vectors


fr_named_vect <- function(x) {   ## Rosenbrock Banana function
    x1 <- x[["a"]]
    x2 <- x[["b"]]
    100 * (x2 - x1 * x1)^2 + (1 - x1)^2
}

pars <- list(a = -1.2, b = 1)

optim(pars, fr_named_vect)
#> $par
#>        a        b 
#> 1.000260 1.000506 
#> 
#> $value
#> [1] 8.825241e-08
#> 
#> $counts
#> function gradient 
#>      195       NA 
#> 
#> $convergence
#> [1] 0
#> 
#> $message
#> NULL
optim(pars, fr_pos)
#> $par
#>        a        b 
#> 1.000260 1.000506 
#> 
#> $value
#> [1] 8.825241e-08
#> 
#> $counts
#> function gradient 
#>      195       NA 
#> 
#> $convergence
#> [1] 0
#> 
#> $message
#> NULL

^{Created on 2025-05-30 with reprex v2.1.1}

Session info

sessioninfo::session_info()
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