```
## Himmelblau function
f_himm <- function(x) (x[1]^2 + x[2] - 11)^2 + (x[1] + x[2]^2 - 7)^2
g_himm <- function(x) {
w1 <- (x[1]^2 + x[2] - 11); w2 <- (x[1] + x[2]^2 - 7)
g1 <- 4*w1*x[1] + 2*w2; g2 <- 2*w1 + 4*w2*x[2]
c(g1, g2)
}
# Find inexact minimum from [6, 6] in the direction [-1, -1] !
softline(c(6, 6), c(-1, -1), f_himm, g_himm)
# [1] 3.458463
# Find the same minimum by using the numerical gradient
softline(c(6, 6), c(-1, -1), f_himm)
# [1] 3.458463
```

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