Sha256: dbe9bcf14c82d9c35aaec90ef948d6090171ac7572aab326024100ff11055e7e
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Size: 993 Bytes
Versions: 4
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Stored size: 993 Bytes
Contents
import "projection";
import "hyperbolic";
function august(λ, φ) {
var tanφ = Math.tan(φ / 2),
k = asqrt(1 - tanφ * tanφ),
c = 1 + k * Math.cos(λ /= 2),
x = Math.sin(λ) * k / c,
y = tanφ / c,
x2 = x * x,
y2 = y * y;
return [
4 / 3 * x * (3 + x2 - 3 * y2),
4 / 3 * y * (3 + 3 * x2 - y2)
];
}
august.invert = function(x, y) {
x *= 3 / 8, y *= 3 / 8;
if (!x && Math.abs(y) > 1) return null;
var x2 = x * x,
y2 = y * y,
s = 1 + x2 + y2,
sin3η = Math.sqrt(.5 * (s - Math.sqrt(s * s - 4 * y * y))),
η = asin(sin3η) / 3,
ξ = sin3η ? arcosh(Math.abs(y / sin3η)) / 3 : arsinh(Math.abs(x)) / 3,
cosη = Math.cos(η),
coshξ = cosh(ξ),
d = coshξ * coshξ - cosη * cosη;
return [
sgn(x) * 2 * Math.atan2(sinh(ξ) * cosη, .25 - d),
sgn(y) * 2 * Math.atan2(coshξ * Math.sin(η), .25 + d)
];
};
(d3.geo.august = function() { return projection(august); }).raw = august;
Version data entries
4 entries across 4 versions & 1 rubygems