Deterministic multistage Beverton-Holt model using nested for loops in Racket

NestedForLoop.rkt

#lang racket/base

;; scalar constants
(define years 30)
(define prop-female 0.5)
(define egg-surv 0.6)

;; age-specific fecundity and survival
(define fecundity #(0 0 200 400 800))
(define survival #(0.2 0.4 0.6 0.8 0)) 
(define capacity #(1e6 1e5 1e4 1e3 1e2))

;; multistage Beverton-Holt model 
(define (beverton-holt N p c)
  (/ N (+ (/ 1 p) (/ N c))))

;; initialize empty results "matrix"
(define results (for/vector ([i (in-range years)]) (make-vector (vector-length fecundity) 0)))

;; initialize abundances in first year to arbitrary non-zero value
(vector-set! results 0 (make-vector (vector-length fecundity) 10))

;; iterate over results to fill "matrix"
(for* ([i (in-range (sub1 years))]
       [j (in-range (vector-length fecundity))])
  ;; current abundance vector
  (define N (vector-ref results i))
  ;; next year abundance vector
  (define Nt (vector-ref results (add1 i)))
  ;; reproduction
  (define fecundity-age-j (vector-ref fecundity j))
  (when (> fecundity-age-j 0)  ;; not all age classes reproduce
    (define N-female (* (vector-ref N j) prop-female))
    ;; next year age-0
    (define Nt-age-0 (vector-ref Nt 0)) 
  
    (define new-age-0 (beverton-holt
                       N-female
                       (* fecundity-age-j egg-surv)
                       (- (vector-ref capacity 0) Nt-age-0)))
    (vector-set! Nt 0 (+ Nt-age-0 new-age-0))
    )
  ;; survival
  (define survival-age-j (vector-ref survival j))
  (when (> survival-age-j 0)
    (define Nt-age-j (vector-ref Nt (add1 j))) 
    (define new-age-j (beverton-holt
                       (vector-ref N j)
                       survival-age-j
                       (- (vector-ref capacity (add1 j)) Nt-age-j)))
    (vector-set! Nt (add1 j) (+ Nt-age-j new-age-j))

    )
  (vector-set! results (add1 i) Nt)
  )
results