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;"determ.scm" Determinant
(define (determinant m)
(define (butnth n lst)
(if (zero? n) (cdr lst) (cons (car lst) (butnth (+ -1 n) (cdr lst)))))
(define (minor m i j)
(map (lambda (x) (butnth j x)) (butnth i m)))
(define (cofactor m i j)
(* (if (odd? (+ i j)) -1 1) (determinant (minor m i j))))
(define n (length m))
(if (eqv? 1 n) (caar m)
(do ((j (+ -1 n) (+ -1 j))
(ans 0 (+ ans (* (list-ref (car m) j) (cofactor m 0 j)))))
((negative? j) ans))))
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