18 lines
502 B
Racket
18 lines
502 B
Racket
#lang racket
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(require math plot)
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(define xs '(0 1 2 3 4 5 6 7 8 9 10))
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(define ys '(1 6 17 34 57 86 121 162 209 262 321))
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(define (fit x y n)
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(define Y (->col-matrix y))
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(define V (vandermonde-matrix x (+ n 1)))
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(define VT (matrix-transpose V))
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(matrix->vector (matrix-solve (matrix* VT V) (matrix* VT Y))))
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(define ((poly v) x)
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(for/sum ([c v] [i (in-naturals)])
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(* c (expt x i))))
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(plot (list (points (map vector xs ys))
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(function (poly (fit xs ys 2)))))
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