29 lines
673 B
Scheme
29 lines
673 B
Scheme
(define (accumulate op initial sequence)
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(if (null? sequence)
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initial
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(op (car sequence)
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(accumulate op initial (cdr sequence)))))
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(define (accumulate-n op init seqs)
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(if (null? (car seqs))
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'()
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(cons (accumulate op init (map car seqs))
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(accumulate-n op init (map cdr seqs)))))
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(define (dot-product v w)
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(accumulate + 0 (map * v w)))
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(define (matrix-*-vector m v)
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(map (lambda (row) (dot-product row v)) m))
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(define (transpose m)
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(accumulate-n cons '() m))
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(define (matrix-*-matrix m n)
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(let ((cols (transpose n)))
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(map (lambda (row)
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(map (lambda (col)
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(dot-product row col))
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cols))
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m)))
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