deriv_n: Extract the k-th derivative from a nested dual result

In nabla: Exact Derivatives via Automatic Differentiation

Extract the k-th derivative from a nested dual result

Description

After evaluating a function on a dual created by dual_variable_n, use deriv_n to extract any derivative from 0 (the function value) up to the seeded order.

Usage

deriv_n(d, k)

Arguments

d	A (possibly nested) dual number, or a numeric.
k	A non-negative integer: 0 for the function value, 1 for the first derivative, etc.

Value

A numeric value.

Examples

x <- dual_variable_n(1, order = 3)
r <- exp(x)
deriv_n(r, 0)
deriv_n(r, 1)
deriv_n(r, 2)
deriv_n(r, 3)

nabla documentation built on Feb. 11, 2026, 1:06 a.m.