Fix float64 comparison test failure on archs using FMA (#1133) · prometheus/client_golang@4d54769 (original) (raw)

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// Permission is hereby granted, free of charge, to any person obtaining a copy

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// of this software and associated documentation files (the "Software"), to deal

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// in the Software without restriction, including without limitation the rights

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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

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// copies of the Software, and to permit persons to whom the Software is

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// furnished to do so, subject to the following conditions:

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// The above copyright notice and this permission notice shall be included in all

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// copies or substantial portions of the Software.

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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

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// SOFTWARE.

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// The code in this package is copy/paste to avoid a dependency. Hence this file

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// carries the copyright of the original repo.

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// https://github.com/beorn7/floats

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package internal

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+

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import (

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"math"

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)

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+

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// minNormalFloat64 is the smallest positive normal value of type float64.

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var minNormalFloat64 = math.Float64frombits(0x0010000000000000)

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+

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// AlmostEqualFloat64 returns true if a and b are equal within a relative error

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// of epsilon. See http://floating-point-gui.de/errors/comparison/ for the

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// details of the applied method.

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func AlmostEqualFloat64(a, b, epsilon float64) bool {

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if a == b {

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return true

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}

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absA := math.Abs(a)

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absB := math.Abs(b)

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diff := math.Abs(a - b)

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if a == 0 || b == 0 || absA+absB < minNormalFloat64 {

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return diff < epsilon*minNormalFloat64

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}

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return diff/math.Min(absA+absB, math.MaxFloat64) < epsilon

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}

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+

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// AlmostEqualFloat64s is the slice form of AlmostEqualFloat64.

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func AlmostEqualFloat64s(a, b []float64, epsilon float64) bool {

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if len(a) != len(b) {

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return false

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}

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for i := range a {

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if !AlmostEqualFloat64(a[i], b[i], epsilon) {

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return false

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}

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}

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return true

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}