egison-3.7.12: sample/math/geometry/exterior-derivative.egi

(define $N 3)
(define $params [| x y z |])
(define $g [| [| 1 0 0 |] [| 0 1 0 |] [| 0 0 1 |] |])

(define $d
  (lambda [%X]
    !((flip ∂/∂) params X)))


(define $f (function [x y z]))

(d f)
;[| f|x f|y f|z |]

(df-normalize (d (d f)))
;[| [| 0 0 0 |] [| 0 0 0 |] [| 0 0 0 |] |]