I have a list of lists [(1 2 3) (4 5 6) (7 8 9)] which is for a matrix. I am looking for how to get the diagonal( which should be (1 5 9). My code provides me with an error "OPERATOR IS NOT A PROCEDURE". i dont know exactly what i did wrong in this. Help would be appreciated.THE CODE IS BELOW.
(define (diagonal lst)
(if(null? lst)
(0)
((cons (list-ref (reverse (car lst)) (- (length lst) 1)) (diagonal (cdr lst))))))
(0) -> you cannot evaluate the procedure 0, because it's not a procedure. Drop the parentheses.
The diagonal of
a b c d
e f g h
c d e f
g h i j
consists of the a (the first element of the first list) followed by the diagonal of
f g h
d e f
h i j
The matrix above consists of the rows of the original matrix with the first row omitted and the first column removed.
(define (diagonal m)
(if (empty-matrix? m)
'()
(cons (first (first m))
(diagonal (remove-first-column (remove-first-row m))))))
(define (remove-first-column m)
...fill-in...)
(define (remove-first-row m)
...fill-in...)
