37 lines
1.1 KiB
Go
37 lines
1.1 KiB
Go
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// CookieJar - A contestant's algorithm toolbox
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// Copyright (c) 2014 Peter Szilagyi. All rights reserved.
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//
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// CookieJar is dual licensed: use of this source code is governed by a BSD
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// license that can be found in the LICENSE file. Alternatively, the CookieJar
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// toolbox may be used in accordance with the terms and conditions contained
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// in a signed written agreement between you and the author(s).
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package curves
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import (
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"math"
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"gopkg.in/karalabe/cookiejar.v2/ai/utility"
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)
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// Sigmoid curve builder, Defined as y = 1 / (slope*e) ^ 10(infl-x).
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type Logistic struct {
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Infl float64 // Point of inflection of the rate of change
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Slope float64 // Multiplier changing the slope of the curve
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Inc bool // Switches between increasing or decreasing curve
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}
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// Creates the curve mapping function.
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func (l Logistic) Make() utility.Curve {
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infl, slope := l.Infl, l.Slope
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if l.Inc {
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return func(x float64) float64 {
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return 1 / (1 + math.Pow(slope*math.E, 10*(infl-x)))
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}
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} else {
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return func(x float64) float64 {
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return 1 - 1/(1+math.Pow(slope*math.E, 10*(infl-x)))
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}
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}
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}
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