I just discover the deriv function but I have a minor problem at the end
when using its result:
For example:
dx2x <- deriv(~ A*x^2, "x") ; dx2x
# it works fine:
# expression({
# .value <- A * x^2
# .grad <- array(0, c(length(.value), 1L), list(NULL, c("x")))
# .grad[, "x"] <- A * (2 * x)
# attr(.value, "gradient") <- .grad
# .value
# })
A <- 3
x <- 23
eval(dx2x)
# great 138 is well the derivative at the point 23
# [1] 1587
# attr(,"gradient")
# x
# [1,] 138
But I don’t know how to get the 138 value.
Any idea ?
Thanks a lot
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