1 files changed, 212 insertions, 0 deletions
diff --git a/vendor/github.com/blevesearch/bleve/geo/sloppy.go b/vendor/github.com/blevesearch/bleve/geo/sloppy.go
new file mode 100644
index 0000000000..0ce646d74a
--- /dev/null
+++ b/vendor/github.com/blevesearch/bleve/geo/sloppy.go
@@ -0,0 +1,212 @@
+//  Copyright (c) 2017 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package geo
+
+import (
+	"math"
+)
+
+var earthDiameterPerLatitude []float64
+var sinTab []float64
+var cosTab []float64
+var asinTab []float64
+var asinDer1DivF1Tab []float64
+var asinDer2DivF2Tab []float64
+var asinDer3DivF3Tab []float64
+var asinDer4DivF4Tab []float64
+
+const radiusTabsSize = (1 << 10) + 1
+const radiusDelta = (math.Pi / 2) / (radiusTabsSize - 1)
+const radiusIndexer = 1 / radiusDelta
+const sinCosTabsSize = (1 << 11) + 1
+const asinTabsSize = (1 << 13) + 1
+const oneDivF2 = 1 / 2.0
+const oneDivF3 = 1 / 6.0
+const oneDivF4 = 1 / 24.0
+
+// 1.57079632673412561417e+00 first 33 bits of pi/2
+var pio2Hi = math.Float64frombits(0x3FF921FB54400000)
+
+// 6.07710050650619224932e-11 pi/2 - PIO2_HI
+var pio2Lo = math.Float64frombits(0x3DD0B4611A626331)
+
+var asinPio2Hi = math.Float64frombits(0x3FF921FB54442D18) // 1.57079632679489655800e+00
+var asinPio2Lo = math.Float64frombits(0x3C91A62633145C07) // 6.12323399573676603587e-17
+var asinPs0 = math.Float64frombits(0x3fc5555555555555)    //  1.66666666666666657415e-01
+var asinPs1 = math.Float64frombits(0xbfd4d61203eb6f7d)    // -3.25565818622400915405e-01
+var asinPs2 = math.Float64frombits(0x3fc9c1550e884455)    //  2.01212532134862925881e-01
+var asinPs3 = math.Float64frombits(0xbfa48228b5688f3b)    // -4.00555345006794114027e-02
+var asinPs4 = math.Float64frombits(0x3f49efe07501b288)    //  7.91534994289814532176e-04
+var asinPs5 = math.Float64frombits(0x3f023de10dfdf709)    //  3.47933107596021167570e-05
+var asinQs1 = math.Float64frombits(0xc0033a271c8a2d4b)    // -2.40339491173441421878e+00
+var asinQs2 = math.Float64frombits(0x40002ae59c598ac8)    //  2.02094576023350569471e+00
+var asinQs3 = math.Float64frombits(0xbfe6066c1b8d0159)    // -6.88283971605453293030e-01
+var asinQs4 = math.Float64frombits(0x3fb3b8c5b12e9282)    //  7.70381505559019352791e-02
+
+var twoPiHi = 4 * pio2Hi
+var twoPiLo = 4 * pio2Lo
+var sinCosDeltaHi = twoPiHi/sinCosTabsSize - 1
+var sinCosDeltaLo = twoPiLo/sinCosTabsSize - 1
+var sinCosIndexer = 1 / (sinCosDeltaHi + sinCosDeltaLo)
+var sinCosMaxValueForIntModulo = ((math.MaxInt64 >> 9) / sinCosIndexer) * 0.99
+var asinMaxValueForTabs = math.Sin(73.0 * degreesToRadian)
+
+var asinDelta = asinMaxValueForTabs / (asinTabsSize - 1)
+var asinIndexer = 1 / asinDelta
+
+func init() {
+	// initializes the tables used for the sloppy math functions
+
+	// sin and cos
+	sinTab = make([]float64, sinCosTabsSize)
+	cosTab = make([]float64, sinCosTabsSize)
+	sinCosPiIndex := (sinCosTabsSize - 1) / 2
+	sinCosPiMul2Index := 2 * sinCosPiIndex
+	sinCosPiMul05Index := sinCosPiIndex / 2
+	sinCosPiMul15Index := 3 * sinCosPiIndex / 2
+	for i := 0; i < sinCosTabsSize; i++ {
+		// angle: in [0,2*PI].
+		angle := float64(i)*sinCosDeltaHi + float64(i)*sinCosDeltaLo
+		sinAngle := math.Sin(angle)
+		cosAngle := math.Cos(angle)
+		// For indexes corresponding to null cosine or sine, we make sure the value is zero
+		// and not an epsilon. This allows for a much better accuracy for results close to zero.
+		if i == sinCosPiIndex {
+			sinAngle = 0.0
+		} else if i == sinCosPiMul2Index {
+			sinAngle = 0.0
+		} else if i == sinCosPiMul05Index {
+			sinAngle = 0.0
+		} else if i == sinCosPiMul15Index {
+			sinAngle = 0.0
+		}
+		sinTab[i] = sinAngle
+		cosTab[i] = cosAngle
+	}
+
+	// asin
+	asinTab = make([]float64, asinTabsSize)
+	asinDer1DivF1Tab = make([]float64, asinTabsSize)
+	asinDer2DivF2Tab = make([]float64, asinTabsSize)
+	asinDer3DivF3Tab = make([]float64, asinTabsSize)
+	asinDer4DivF4Tab = make([]float64, asinTabsSize)
+	for i := 0; i < asinTabsSize; i++ {
+		// x: in [0,ASIN_MAX_VALUE_FOR_TABS].
+		x := float64(i) * asinDelta
+		asinTab[i] = math.Asin(x)
+		oneMinusXSqInv := 1.0 / (1 - x*x)
+		oneMinusXSqInv05 := math.Sqrt(oneMinusXSqInv)
+		oneMinusXSqInv15 := oneMinusXSqInv05 * oneMinusXSqInv
+		oneMinusXSqInv25 := oneMinusXSqInv15 * oneMinusXSqInv
+		oneMinusXSqInv35 := oneMinusXSqInv25 * oneMinusXSqInv
+		asinDer1DivF1Tab[i] = oneMinusXSqInv05
+		asinDer2DivF2Tab[i] = (x * oneMinusXSqInv15) * oneDivF2
+		asinDer3DivF3Tab[i] = ((1 + 2*x*x) * oneMinusXSqInv25) * oneDivF3
+		asinDer4DivF4Tab[i] = ((5 + 2*x*(2+x*(5-2*x))) * oneMinusXSqInv35) * oneDivF4
+	}
+
+	// earth radius
+	a := 6378137.0
+	b := 6356752.31420
+	a2 := a * a
+	b2 := b * b
+	earthDiameterPerLatitude = make([]float64, radiusTabsSize)
+	earthDiameterPerLatitude[0] = 2.0 * a / 1000
+	earthDiameterPerLatitude[radiusTabsSize-1] = 2.0 * b / 1000
+	for i := 1; i < radiusTabsSize-1; i++ {
+		lat := math.Pi * float64(i) / (2*radiusTabsSize - 1)
+		one := math.Pow(a2*math.Cos(lat), 2)
+		two := math.Pow(b2*math.Sin(lat), 2)
+		three := math.Pow(float64(a)*math.Cos(lat), 2)
+		four := math.Pow(b*math.Sin(lat), 2)
+		radius := math.Sqrt((one + two) / (three + four))
+		earthDiameterPerLatitude[i] = 2 * radius / 1000
+	}
+}
+
+// earthDiameter returns an estimation of the earth's diameter at the specified
+// latitude in kilometers
+func earthDiameter(lat float64) float64 {
+	index := math.Mod(math.Abs(lat)*radiusIndexer+0.5, float64(len(earthDiameterPerLatitude)))
+	if math.IsNaN(index) {
+		return 0
+	}
+	return earthDiameterPerLatitude[int(index)]
+}
+
+var pio2 = math.Pi / 2
+
+func sin(a float64) float64 {
+	return cos(a - pio2)
+}
+
+// cos is a sloppy math (faster) implementation of math.Cos
+func cos(a float64) float64 {
+	if a < 0.0 {
+		a = -a
+	}
+	if a > sinCosMaxValueForIntModulo {
+		return math.Cos(a)
+	}
+	// index: possibly outside tables range.
+	index := int(a*sinCosIndexer + 0.5)
+	delta := (a - float64(index)*sinCosDeltaHi) - float64(index)*sinCosDeltaLo
+	// Making sure index is within tables range.
+	// Last value of each table is the same than first, so we ignore it (tabs size minus one) for modulo.
+	index &= (sinCosTabsSize - 2) // index % (SIN_COS_TABS_SIZE-1)
+	indexCos := cosTab[index]
+	indexSin := sinTab[index]
+	return indexCos + delta*(-indexSin+delta*(-indexCos*oneDivF2+delta*(indexSin*oneDivF3+delta*indexCos*oneDivF4)))
+}
+
+// asin is a sloppy math (faster) implementation of math.Asin
+func asin(a float64) float64 {
+	var negateResult bool
+	if a < 0 {
+		a = -a
+		negateResult = true
+	}
+	if a <= asinMaxValueForTabs {
+		index := int(a*asinIndexer + 0.5)
+		delta := a - float64(index)*asinDelta
+		result := asinTab[index] + delta*(asinDer1DivF1Tab[index]+delta*(asinDer2DivF2Tab[index]+delta*(asinDer3DivF3Tab[index]+delta*asinDer4DivF4Tab[index])))
+		if negateResult {
+			return -result
+		}
+		return result
+	}
+	// value > ASIN_MAX_VALUE_FOR_TABS, or value is NaN
+	// This part is derived from fdlibm.
+	if a < 1 {
+		t := (1.0 - a) * 0.5
+		p := t * (asinPs0 + t*(asinPs1+t*(asinPs2+t*(asinPs3+t*(asinPs4+t+asinPs5)))))
+		q := 1.0 + t*(asinQs1+t*(asinQs2+t*(asinQs3+t*asinQs4)))
+		s := math.Sqrt(t)
+		z := s + s*(p/q)
+		result := asinPio2Hi - ((z + z) - asinPio2Lo)
+		if negateResult {
+			return -result
+		}
+		return result
+	}
+	// value >= 1.0, or value is NaN
+	if a == 1.0 {
+		if negateResult {
+			return -math.Pi / 2
+		}
+		return math.Pi / 2
+	}
+	return math.NaN()
+}