58 lines
1.0 KiB
Go
58 lines
1.0 KiB
Go
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// Copyright 2015 The Go Authors. All rights reserved.
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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 stats
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// DeltaDist is the Dirac delta function, centered at T, with total
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// area 1.
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//
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// The CDF of the Dirac delta function is the Heaviside step function,
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// centered at T. Specifically, f(T) == 1.
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type DeltaDist struct {
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T float64
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}
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func (d DeltaDist) PDF(x float64) float64 {
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if x == d.T {
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return inf
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}
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return 0
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}
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func (d DeltaDist) pdfEach(xs []float64) []float64 {
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res := make([]float64, len(xs))
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for i, x := range xs {
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if x == d.T {
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res[i] = inf
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}
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}
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return res
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}
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func (d DeltaDist) CDF(x float64) float64 {
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if x >= d.T {
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return 1
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}
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return 0
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}
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func (d DeltaDist) cdfEach(xs []float64) []float64 {
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res := make([]float64, len(xs))
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for i, x := range xs {
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res[i] = d.CDF(x)
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}
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return res
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}
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func (d DeltaDist) InvCDF(y float64) float64 {
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if y < 0 || y > 1 {
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return nan
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}
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return d.T
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}
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func (d DeltaDist) Bounds() (float64, float64) {
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return d.T - 1, d.T + 1
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}
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