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@@ -1,34 +0,0 @@ |
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package main |
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import "math" |
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// haversin(θ) function |
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func hsin(theta float64) float64 { |
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return math.Pow(math.Sin(theta/2), 2) |
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} |
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// Distance function returns the distance (in meters) between two points of |
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// a given longitude and latitude relatively accurately (using a spherical |
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// approximation of the Earth) through the Haversin Distance Formula for |
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// great arc distance on a sphere with accuracy for small distances |
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// |
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// point coordinates are supplied in degrees and converted into rad. in the func |
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// |
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// distance returned is METERS!!!!!! |
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// http://en.wikipedia.org/wiki/Haversine_formula |
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func Distance(lat1, lon1, lat2, lon2 float64) float64 { |
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// convert to radians |
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// must cast radius as float to multiply later |
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var la1, lo1, la2, lo2, r float64 |
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la1 = lat1 * math.Pi / 180 |
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lo1 = lon1 * math.Pi / 180 |
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la2 = lat2 * math.Pi / 180 |
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lo2 = lon2 * math.Pi / 180 |
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r = 6378100 // Earth radius in METERS |
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// calculate |
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h := hsin(la2-la1) + math.Cos(la1)*math.Cos(la2)*hsin(lo2-lo1) |
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return 2 * r * math.Asin(math.Sqrt(h)) |
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} |