github.com/cockroachdb/cockroachdb-parser@v0.23.3-0.20240213214944-911057d40c9a/pkg/geo/latlng.go (about)

     1  // Copyright 2020 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package geo
    12  
    13  import "math"
    14  
    15  // NormalizeLatitudeDegrees normalizes latitudes to the range [-90, 90].
    16  func NormalizeLatitudeDegrees(lat float64) float64 {
    17  	// math.Remainder(lat, 360) returns in the range [-180, 180].
    18  	lat = math.Remainder(lat, 360)
    19  	// If we are above 90 degrees, we curve back to 0, e.g. 91 -> 89, 100 -> 80.
    20  	if lat > 90 {
    21  		return 180 - lat
    22  	}
    23  	// If we are below 90 degrees, we curve back towards 0, e.g. -91 -> -89, -100 -> -80.
    24  	if lat < -90 {
    25  		return -180 - lat
    26  	}
    27  	return lat
    28  }
    29  
    30  // NormalizeLongitudeDegrees normalizes longitude to the range [-180, 180].
    31  func NormalizeLongitudeDegrees(lng float64) float64 {
    32  	// math.Remainder(lng, 360) returns in the range [-180, 180].
    33  	return math.Remainder(lng, 360)
    34  }