34 lines
1 KiB
Go
34 lines
1 KiB
Go
// Copyright © 2016 Abcum Ltd
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//
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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 geof
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import (
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"math"
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"github.com/abcum/surreal/sql"
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)
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const earthr float64 = 6371000
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const radian float64 = math.Pi / 180
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func Haversine(a, b *sql.Point) float64 {
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lata, lnga := a.LA*radian, a.LO*radian
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latb, lngb := b.LA*radian, b.LO*radian
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latc, lngc := lata-latb, lnga-lngb
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dis := math.Pow(math.Sin(latc/2), 2) + math.Cos(lata)*math.Cos(latb)*math.Pow(math.Sin(lngc/2), 2)
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c := 2 * math.Atan2(math.Sqrt(dis), math.Sqrt(1-dis))
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return earthr * c
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}
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