Sha256: c9d3720ac8c4047f0bf41862103278cc3c614f695329847638421baed86ecc3c
Contents?: true
Size: 869 Bytes
Versions: 4
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Stored size: 869 Bytes
Contents
import "projection";
function polyconic(λ, φ) {
if (Math.abs(φ) < ε) return [λ, 0];
var tanφ = Math.tan(φ),
k = λ * Math.sin(φ);
return [
Math.sin(k) / tanφ,
φ + (1 - Math.cos(k)) / tanφ
];
}
polyconic.invert = function(x, y) {
if (Math.abs(y) < ε) return [x, 0];
var k = x * x + y * y,
φ = y * .5,
i = 10, δ;
do {
var tanφ = Math.tan(φ),
secφ = 1 / Math.cos(φ),
j = k - 2 * y * φ + φ * φ;
φ -= δ = (tanφ * j + 2 * (φ - y)) / (2 + j * secφ * secφ + 2 * (φ - y) * tanφ);
} while (Math.abs(δ) > ε && --i > 0);
tanφ = Math.tan(φ);
return [
(Math.abs(y) < Math.abs(φ + 1 / tanφ) ? asin(x * tanφ) : sgn(x) * (acos(Math.abs(x * tanφ)) + π / 2)) / Math.sin(φ),
φ
];
};
(d3.geo.polyconic = function() { return projection(polyconic); }).raw = polyconic;
Version data entries
4 entries across 4 versions & 1 rubygems