34 lines
819 B
Scheme
34 lines
819 B
Scheme
(define (iterative-improve good-enough? improve)
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(lambda (first-guess)
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(define (try guess)
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(let ((improved-guess (improve guess)))
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(if (good-enough? guess improved-guess)
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guess
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(try improved-guess))))
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(try first-guess)))
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(define (sqrt-ave x)
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(define (good-enough? x y)
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(let ((tolerance 0.00001))
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(< (abs (- x y)) tolerance)))
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(define (improve guess)
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(average guess (/ x guess)))
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((iterative-improve good-enough? improve) 1.0))
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(define (average x y)
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(/ (+ x y) 2))
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(define (fixed-point f first-guess)
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(define (close-enough? v1 v2)
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(< (abs (- v1 v2)) tolerance))
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((iterative-improve close-enough? f)
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first-guess))
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(define (average-damp f)
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(lambda (x) (average x (f x))))
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(define (sqrt-fp x)
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(fixed-point (average-damp (lambda (y) (/ x y)))
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1.0))
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