Sha256: 8275c9df082b8385d725e01b6380f6539ca66b3574088c34a57fc3cb942e35fd
Contents?: true
Size: 929 Bytes
Versions: 4
Compression:
Stored size: 929 Bytes
Contents
import "projection";
var bakerφ = Math.log(1 + Math.SQRT2);
function baker(λ, φ) {
var φ0 = Math.abs(φ);
return φ0 < π / 4
? [λ, Math.log(Math.tan(π / 4 + φ / 2))]
: [
λ * Math.cos(φ0) * (2 * Math.SQRT2 - 1 / Math.sin(φ0)),
sgn(φ) * (2 * Math.SQRT2 * (φ0 - π / 4) - Math.log(Math.tan(φ0 / 2)))
];
}
baker.invert = function(x, y) {
if ((y0 = Math.abs(y)) < bakerφ) return [x, 2 * Math.atan(Math.exp(y)) - π / 2];
var sqrt8 = Math.sqrt(8),
φ = π / 4, i = 25, δ, y0;
do {
var cosφ_2 = Math.cos(φ / 2),
tanφ_2 = Math.tan(φ / 2);
φ -= δ = (sqrt8 * (φ - π / 4) - Math.log(tanφ_2) - y0) / (sqrt8 - .5 * cosφ_2 * cosφ_2 / tanφ_2);
} while (Math.abs(δ) > ε2 && --i > 0);
return [
x / (Math.cos(φ) * (sqrt8 - 1 / Math.sin(φ))),
sgn(y) * φ
];
};
(d3.geo.baker = function() { return projection(baker); }).raw = baker;
Version data entries
4 entries across 4 versions & 1 rubygems