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41 lines
1.3 KiB
41 lines
1.3 KiB
// Copyright 2024 The Prometheus Authors |
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// Licensed under the Apache License, Version 2.0 (the "License"); |
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// you may not use this file except in compliance with the License. |
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// You may obtain a copy of the License at |
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// |
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// http://www.apache.org/licenses/LICENSE-2.0 |
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// |
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// Unless required by applicable law or agreed to in writing, software |
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// distributed under the License is distributed on an "AS IS" BASIS, |
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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// See the License for the specific language governing permissions and |
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// limitations under the License. |
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package almost |
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import "math" |
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var minNormal = math.Float64frombits(0x0010000000000000) // The smallest positive normal value of type float64. |
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// Equal returns true if a and b differ by less than their sum |
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// multiplied by epsilon. |
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func Equal(a, b, epsilon float64) bool { |
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// NaN has no equality but for testing we still want to know whether both values |
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// are NaN. |
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if math.IsNaN(a) && math.IsNaN(b) { |
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return true |
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} |
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// Cf. http://floating-point-gui.de/errors/comparison/ |
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if a == b { |
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return true |
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} |
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absSum := math.Abs(a) + math.Abs(b) |
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diff := math.Abs(a - b) |
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if a == 0 || b == 0 || absSum < minNormal { |
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return diff < epsilon*minNormal |
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} |
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return diff/math.Min(absSum, math.MaxFloat64) < epsilon |
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}
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