66 lines
1.3 KiB
Text
66 lines
1.3 KiB
Text
; helper function that returns rest of matrix by col/row
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(define (rest matrix i j)
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(define (exclude1 l x) (append (take l (- x 1)) (drop l x)))
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(exclude1
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(map exclude1
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matrix (repeat i (length matrix)))
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j))
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; superfunction for determinant and permanent
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(define (super matrix math)
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(let loop ((n (length matrix)) (matrix matrix))
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(if (eq? n 1)
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(caar matrix)
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(fold (lambda (x a j)
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(+ x (* a (lref math (mod j 2)) (super (rest matrix j 1) math))))
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0
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(car matrix)
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(iota n 1)))))
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; det/per calculators
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(define (det matrix) (super matrix '(-1 1)))
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(define (per matrix) (super matrix '( 1 1)))
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; ---=( testing )=---------------------
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(print (det '(
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(1 2)
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(3 4))))
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; ==> -2
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(print (per '(
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(1 2)
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(3 4))))
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; ==> 10
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(print (det '(
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( 1 2 3 1)
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(-1 -1 -1 2)
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( 1 3 1 1)
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(-2 -2 0 -1))))
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; ==> 26
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(print (per '(
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( 1 2 3 1)
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(-1 -1 -1 2)
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( 1 3 1 1)
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(-2 -2 0 -1))))
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; ==> -10
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(print (det '(
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( 0 1 2 3 4)
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( 5 6 7 8 9)
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(10 11 12 13 14)
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(15 16 17 18 19)
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(20 21 22 23 24))))
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; ==> 0
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(print (per '(
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( 0 1 2 3 4)
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( 5 6 7 8 9)
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(10 11 12 13 14)
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(15 16 17 18 19)
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(20 21 22 23 24))))
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; ==> 6778800
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