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import projection from "./index.js";
import {abs, asin, cos, epsilon2, sin, sqrt} from "../math.js";
var A1 = 1.340264,
A2 = -0.081106,
A3 = 0.000893,
A4 = 0.003796,
M = sqrt(3) / 2,
iterations = 12;
export function equalEarthRaw(lambda, phi) {
var l = asin(M * sin(phi)), l2 = l * l, l6 = l2 * l2 * l2;
return [
lambda * cos(l) / (M * (A1 + 3 * A2 * l2 + l6 * (7 * A3 + 9 * A4 * l2))),
l * (A1 + A2 * l2 + l6 * (A3 + A4 * l2))
];
}
equalEarthRaw.invert = function(x, y) {
var l = y, l2 = l * l, l6 = l2 * l2 * l2;
for (var i = 0, delta, fy, fpy; i < iterations; ++i) {
fy = l * (A1 + A2 * l2 + l6 * (A3 + A4 * l2)) - y;
fpy = A1 + 3 * A2 * l2 + l6 * (7 * A3 + 9 * A4 * l2);
l -= delta = fy / fpy, l2 = l * l, l6 = l2 * l2 * l2;
if (abs(delta) < epsilon2) break;
}
return [
M * x * (A1 + 3 * A2 * l2 + l6 * (7 * A3 + 9 * A4 * l2)) / cos(l),
asin(sin(l) / M)
];
};
export default function() {
return projection(equalEarthRaw)
.scale(177.158);
}