forked from mirror/client_golang
37 lines
861 B
Go
37 lines
861 B
Go
// Copyright (c) 2013, Prometheus Team
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// All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package prometheus
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import (
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"math"
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)
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// Go's standard library does not offer a factorial function.
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func factorial(of int) int64 {
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if of <= 0 {
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return 1
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}
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var result int64 = 1
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for i := int64(of); i >= 1; i-- {
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result *= i
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}
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return result
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}
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// Calculate the value of a probability density for a given binomial statistic,
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// where k is the target count of true cases, n is the number of subjects, and
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// p is the probability.
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func binomialPDF(k, n int, p float64) float64 {
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binomialCoefficient := float64(factorial(n)) / float64(factorial(k)*factorial(n-k))
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intermediate := math.Pow(p, float64(k)) * math.Pow(1-p, float64(n-k))
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return binomialCoefficient * intermediate
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}
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