partial-derivative-symbol

∂ (Partial derivative symbol) - The ∂ symbol indicates a partial derivative, as in . It generalises differentiation to functions of multiple variables (see partial-derivative).

Key points:

• ∂ is distinct from d in single-variable calculus.
• Common in PDEs (partial differential equations).

No direct R demonstration needed here, but partial derivatives can be approximated numerically.

library(data.table)
 
f_xy <- function(x,y) x^2 + 3*x*y
partial_x <- function(f, x, y, h=1e-6) (f(x+h,y)-f(x,y))/h
partial_x(f_xy, 2, 3)

## [1] 13