import "../core/noop";

import "../math/trigonometry";

import "geo";

import "stream";

d3.geo.length = function(object) {

d3_geo_lengthSum = 0;

d3.geo.stream(object, d3_geo_length);

return d3_geo_lengthSum;

};

var d3_geo_lengthSum;

var d3_geo_length = {

sphere: d3_noop,

point: d3_noop,

lineStart: d3_geo_lengthLineStart,

lineEnd: d3_noop,

polygonStart: d3_noop,

polygonEnd: d3_noop

};

function d3_geo_lengthLineStart() {

var λ0, sinφ0, cosφ0;

d3_geo_length.point = function(λ, φ) {

λ0 = λ * d3_radians, sinφ0 = Math.sin(φ *= d3_radians), cosφ0 = Math.cos(φ);

d3_geo_length.point = nextPoint;

};

d3_geo_length.lineEnd = function() {

d3_geo_length.point = d3_geo_length.lineEnd = d3_noop;

};

function nextPoint(λ, φ) {

var sinφ = Math.sin(φ *= d3_radians),

cosφ = Math.cos(φ),

t = Math.abs((λ *= d3_radians) - λ0),

cosΔλ = Math.cos(t);

d3_geo_lengthSum += Math.atan2(Math.sqrt((t = cosφ * Math.sin(t)) * t + (t = cosφ0 * sinφ - sinφ0 * cosφ * cosΔλ) * t), sinφ0 * sinφ + cosφ0 * cosφ * cosΔλ);

λ0 = λ, sinφ0 = sinφ, cosφ0 = cosφ;

}

}