| 1 | // code duplicated from d3-geo-projection
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| 2 | import {asin, pi, sin, sqrt, sqrtPi} from "./math.js";
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| 3 |
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| 4 | export function collignonRaw(lambda, phi) {
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| 5 | var alpha = sqrt(1 - sin(phi));
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| 6 | return [(2 / sqrtPi) * lambda * alpha, sqrtPi * (1 - alpha)];
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| 7 | }
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| 8 |
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| 9 | collignonRaw.invert = function(x, y) {
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| 10 | var lambda = (lambda = y / sqrtPi - 1) * lambda;
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| 11 | return [lambda > 0 ? x * sqrt(pi / lambda) / 2 : 0, asin(1 - lambda)];
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| 12 | };
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